diff --git a/src/import_resolver.rs b/src/import_resolver.rs
new file mode 100644
index 0000000..7852dc3
--- /dev/null
+++ b/src/import_resolver.rs
@@ -0,0 +1,410 @@
+use crate::ast::{ASTNode, ASTNodeKind, Span};
+use crate::lexer::Token;
+use crate::parser::Parser;
+use logos::Logos;
+use std::collections::{HashMap, HashSet};
+use std::fs;
+use std::path::Path;
+
+const EXTENSION: &str = ".sui";
+
+/// Error types for import resolution
+#[derive(Debug, Clone)]
+pub enum ImportError {
+    DuplicateSymbol {
+        symbol: String,
+        locations: Vec<String>,
+    },
+    FileNotFound {
+        path: String,
+        reason: String,
+    },
+    LexError {
+        file: String,
+        position: usize,
+    },
+    ParseError {
+        file: String,
+        message: String,
+        span: (usize, usize),
+    },
+    CircularDependency {
+        files: Vec<String>,
+    },
+}
+
+impl std::fmt::Display for ImportError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            ImportError::DuplicateSymbol { symbol, locations } => {
+                write!(f, "Duplicate global symbol '{}' defined in:\n", symbol)?;
+                for (i, loc) in locations.iter().enumerate() {
+                    write!(f, "  [{}] {}", i + 1, loc)?;
+                    if i < locations.len() - 1 {
+                        writeln!(f)?;
+                    }
+                }
+                Ok(())
+            }
+            ImportError::FileNotFound { path, reason } => {
+                write!(f, "Module not found '{}': {}", path, reason)
+            }
+            ImportError::LexError { file, position } => {
+                write!(f, "Lexer error at position {} in {}", position, file)
+            }
+            ImportError::ParseError {
+                file,
+                message,
+                span,
+            } => {
+                write!(
+                    f,
+                    "Parse error in {}: {} (at {}..{})",
+                    file, message, span.0, span.1
+                )
+            }
+            ImportError::CircularDependency { files } => {
+                write!(f, "Circular dependency detected: {}", files.join(" -> "))
+            }
+        }
+    }
+}
+
+impl std::error::Error for ImportError {}
+
+/// Cached parse output for a file
+#[derive(Clone, Debug)]
+struct ParsedFile {
+    /// AST nodes from this file (before import collection)
+    nodes: Vec<ASTNode>,
+    /// Hash of the file content at parse time
+    content_hash: u64,
+}
+
+/// Tracks global symbols and their definitions
+#[derive(Debug, Default)]
+struct GlobalSymbolRegistry {
+    /// Maps symbol name to (file, span) where it was defined
+    symbols: HashMap<String, Vec<(String, Span)>>,
+}
+
+impl GlobalSymbolRegistry {
+    fn register(&mut self, symbol: String, file: String, span: Span) -> Result<(), ImportError> {
+        self.symbols.entry(symbol.clone()).or_insert_with(Vec::new);
+        let locations = self.symbols.get_mut(&symbol).unwrap();
+
+        locations.push((file.clone(), span));
+
+        // Check for duplicates
+        if locations.len() > 1 {
+            let location_strs = locations
+                .iter()
+                .map(|(f, s)| format!("{}:{}..{}", f, s.start, s.end))
+                .collect();
+
+            return Err(ImportError::DuplicateSymbol {
+                symbol,
+                locations: location_strs,
+            });
+        }
+
+        Ok(())
+    }
+}
+
+/// Manages file dependency resolution and caching
+pub struct ImportResolver {
+    /// Cache of parsed files keyed by path
+    parse_cache: HashMap<String, ParsedFile>,
+    /// Global symbol registry for duplicate detection
+    symbol_registry: GlobalSymbolRegistry,
+    /// Set of files currently being processed (for cycle detection)
+    processing_stack: HashSet<String>,
+    /// Dependency graph: file -> list of files it depends on
+    dependency_graph: HashMap<String, HashSet<String>>,
+}
+
+impl ImportResolver {
+    pub fn new() -> Self {
+        ImportResolver {
+            parse_cache: HashMap::new(),
+            symbol_registry: GlobalSymbolRegistry::default(),
+            processing_stack: HashSet::new(),
+            dependency_graph: HashMap::new(),
+        }
+    }
+
+    /// Compute a simple hash of file content
+    fn hash_content(content: &str) -> u64 {
+        use std::collections::hash_map::DefaultHasher;
+        use std::hash::{Hash, Hasher};
+
+        let mut hasher = DefaultHasher::new();
+        content.hash(&mut hasher);
+        hasher.finish()
+    }
+
+    /// Lex source code into tokens
+    fn lex_source(source: &str, filename: &str) -> Result<Vec<(Token, logos::Span)>, ImportError> {
+        let mut tokens = Vec::new();
+        let mut lexer = Token::lexer(source);
+
+        while let Some(token_result) = lexer.next() {
+            match token_result {
+                Ok(token) => {
+                    tokens.push((token, lexer.span()));
+                }
+                Err(()) => {
+                    return Err(ImportError::LexError {
+                        file: filename.to_string(),
+                        position: lexer.span().start,
+                    });
+                }
+            }
+        }
+
+        Ok(tokens)
+    }
+
+    /// Parse tokens into AST
+    fn parse_tokens(
+        tokens: Vec<(Token, logos::Span)>,
+        filename: String,
+    ) -> Result<Vec<ASTNode>, ImportError> {
+        let mut parser = Parser::new(filename.clone(), tokens);
+        parser.parse().map_err(|e| ImportError::ParseError {
+            file: filename,
+            message: e.message.clone(),
+            span: (e.span.start, e.span.end),
+        })
+    }
+
+    /// Parse a file (using cache if content hash matches)
+    fn parse_file(&mut self, filename: &str) -> Result<Vec<ASTNode>, ImportError> {
+        let source = fs::read_to_string(filename).map_err(|e| ImportError::FileNotFound {
+            path: filename.to_string(),
+            reason: e.to_string(),
+        })?;
+
+        let content_hash = Self::hash_content(&source);
+
+        // Check if we have a valid cached version
+        if let Some(cached) = self.parse_cache.get(filename) {
+            if cached.content_hash == content_hash {
+                println!("  [cache hit] {}", filename);
+                return Ok(cached.nodes.clone());
+            }
+        }
+
+        // Parse the file
+        println!("  [parsing] {}", filename);
+        let tokens = Self::lex_source(&source, filename)?;
+        let nodes = Self::parse_tokens(tokens, filename.to_string())?;
+
+        // Cache the result
+        self.parse_cache.insert(
+            filename.to_string(),
+            ParsedFile {
+                nodes: nodes.clone(),
+                content_hash,
+            },
+        );
+
+        Ok(nodes)
+    }
+
+    /// Collect all dependencies from a file (via Use/Load statements)
+    fn collect_dependencies(&self, filename: &str, nodes: &[ASTNode]) -> Vec<String> {
+        let mut deps = Vec::new();
+        let mut seen = HashSet::new();
+
+        for node in nodes {
+            if let ASTNodeKind::Use(use_stmt) = &node.kind {
+                let path = &use_stmt.path;
+                if !seen.contains(path) {
+                    seen.insert(path.clone());
+                    deps.push(path.clone());
+                }
+            }
+        }
+
+        // Resolve relative paths
+        let importing_dir = Path::new(filename).parent().unwrap_or(Path::new(""));
+
+        deps.iter()
+            .filter_map(|path| {
+                let resolved = if path.starts_with("std/") {
+                    Some(format!("src/{}{}", path, EXTENSION))
+                } else if path.starts_with("@") {
+                    // Package manager support - TODO
+                    None
+                } else if path.starts_with(".") || path.starts_with("~") {
+                    let resolved_path = importing_dir.join(path);
+                    Some(resolved_path.to_string_lossy().to_string() + EXTENSION)
+                } else {
+                    None
+                };
+                resolved
+            })
+            .collect()
+    }
+
+    /// Check for circular dependencies
+    fn detect_cycles(&self, file: &str, target: &str) -> Result<(), ImportError> {
+        if file == target {
+            return Err(ImportError::CircularDependency {
+                files: vec![file.to_string()],
+            });
+        }
+
+        // Simple cycle detection: if target depends on file, we have a cycle
+        if let Some(target_deps) = self.dependency_graph.get(target) {
+            if target_deps.contains(file) {
+                return Err(ImportError::CircularDependency {
+                    files: vec![file.to_string(), target.to_string()],
+                });
+            }
+        }
+
+        Ok(())
+    }
+
+    /// Recursively resolve imports for a file
+    fn resolve_imports_recursive(&mut self, filename: &str) -> Result<Vec<ASTNode>, ImportError> {
+        // Check for cycles in processing
+        if self.processing_stack.contains(filename) {
+            return Err(ImportError::CircularDependency {
+                files: self
+                    .processing_stack
+                    .iter()
+                    .cloned()
+                    .collect::<Vec<_>>()
+                    .into_iter()
+                    .chain(std::iter::once(filename.to_string()))
+                    .collect(),
+            });
+        }
+
+        self.processing_stack.insert(filename.to_string());
+
+        // Parse the file
+        let nodes = self.parse_file(filename)?;
+        let mut result = Vec::new();
+
+        // Collect dependencies
+        let deps = self.collect_dependencies(filename, &nodes);
+        self.dependency_graph
+            .insert(filename.to_string(), deps.iter().cloned().collect());
+
+        // Process each node
+        for node in nodes {
+            match &node.kind {
+                ASTNodeKind::Use(use_stmt) => {
+                    let path = &use_stmt.path;
+
+                    // Resolve path
+                    let dep_file = if path.starts_with("std/") {
+                        format!("src/{}{}", path, EXTENSION)
+                    } else if path.starts_with("@") {
+                        // Package manager support - TODO
+                        todo!("Package manager imports not yet supported")
+                    } else if path.starts_with(".") || path.starts_with("~") {
+                        let importing_dir = Path::new(filename).parent().unwrap_or(Path::new(""));
+                        let resolved_path = importing_dir.join(path);
+                        resolved_path.to_string_lossy().to_string() + EXTENSION
+                    } else {
+                        return Err(ImportError::FileNotFound {
+                            path: path.clone(),
+                            reason: "Invalid import path format".to_string(),
+                        });
+                    };
+
+                    // Check for cycles
+                    self.detect_cycles(filename, &dep_file)?;
+
+                    // Recursively resolve the imported file
+                    let imported_nodes = self.resolve_imports_recursive(&dep_file)?;
+                    result.extend(imported_nodes);
+                }
+                ASTNodeKind::Struct(s) => {
+                    // Register the symbol
+                    self.symbol_registry.register(
+                        s.name.clone(),
+                        filename.to_string(),
+                        node.span.clone(),
+                    )?;
+                    result.push(node);
+                }
+                ASTNodeKind::Enum(e) => {
+                    self.symbol_registry.register(
+                        e.name.clone(),
+                        filename.to_string(),
+                        node.span.clone(),
+                    )?;
+                    result.push(node);
+                }
+                ASTNodeKind::Function(f) => {
+                    self.symbol_registry.register(
+                        f.name.clone(),
+                        filename.to_string(),
+                        node.span.clone(),
+                    )?;
+                    result.push(node);
+                }
+                ASTNodeKind::Impl(_) => {
+                    // Impl blocks don't have names but are still tracked
+                    result.push(node);
+                }
+                ASTNodeKind::Extern(e) => {
+                    self.symbol_registry.register(
+                        e.name.clone(),
+                        filename.to_string(),
+                        node.span.clone(),
+                    )?;
+                    result.push(node);
+                }
+                ASTNodeKind::Load(_) => {
+                    result.push(node);
+                }
+                ASTNodeKind::Trait(t) => {
+                    self.symbol_registry.register(
+                        t.name.clone(),
+                        filename.to_string(),
+                        node.span.clone(),
+                    )?;
+                    result.push(node);
+                }
+            }
+        }
+
+        self.processing_stack.remove(filename);
+        Ok(result)
+    }
+
+    /// Resolve all imports starting from the given file
+    pub fn resolve(&mut self, filename: &str) -> Result<Vec<ASTNode>, ImportError> {
+        println!("Starting import resolution...");
+        self.resolve_imports_recursive(filename)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_hash_content() {
+        let content1 = "fn main() do end";
+        let content2 = "fn main() do end";
+        let content3 = "fn main() { x }";
+
+        assert_eq!(
+            ImportResolver::hash_content(content1),
+            ImportResolver::hash_content(content2)
+        );
+        assert_ne!(
+            ImportResolver::hash_content(content1),
+            ImportResolver::hash_content(content3)
+        );
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 6da9abc..a9fac3c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -4,6 +4,7 @@ pub mod ast;
 pub mod c_ir;
 pub mod c_lowerer;
 pub mod codegen;
+pub mod import_resolver;
 pub mod lambda_lower;
 pub mod lexer;
 pub mod monomorphize;
diff --git a/src/main.rs b/src/main.rs
index 587e7c0..f4df3d9 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,11 +1,9 @@
-use logos::Logos;
 use std::fs;
 use suicmez::{
     codegen::transpiler::Transpiler,
+    import_resolver::ImportResolver,
     lambda_lower::LambdaLowerer,
-    lexer::Token,
     monomorphize::{Monomorphizer, check_no_typevars},
-    parser::Parser,
     typechecker::TypeChecker,
 };
 
@@ -164,34 +162,19 @@ fn format_type_error(source: &str, error: &suicmez::typechecker::TypeError) -> S
 }
 
 fn run_file(filename: &str) -> Result<(), String> {
-    // Read the source file
+    // ========== IMPORT RESOLUTION PHASE ==========
+    println!("\n=== Import Resolution Phase ===");
+    let mut resolver = ImportResolver::new();
+    let ast_nodes = resolver
+        .resolve(filename)
+        .map_err(|e| format!("Import resolution error: {}", e))?;
+
+    println!("Import resolution complete! {} total nodes loaded", ast_nodes.len());
+    
+    // Read the source file for error reporting
     let source = fs::read_to_string(filename)
         .map_err(|e| format!("Error reading file {}: {}", filename, e))?;
 
-    // First, we need to parse the source code
-    let mut tokens = Vec::new();
-    let mut lexer = Token::lexer(&source);
-
-    loop {
-        match lexer.next() {
-            Some(Ok(token)) => {
-                let span = lexer.span();
-                tokens.push((token, span));
-            }
-            Some(Err(_)) => {
-                return Err("Lexing error".to_string());
-            }
-            None => break,
-        }
-    }
-
-    let mut parser = Parser::new(filename.to_string(), tokens);
-    let ast_nodes = parser
-        .parse()
-        .map_err(|e| format_parse_error(&source, &e))?;
-
-    println!("Parsed {} AST nodes successfully", ast_nodes.len());
-
     // Lower lambdas to generated functions
     let lowerer = LambdaLowerer::new();
     let lowered_nodes = lowerer
diff --git a/tests/import_tests/duplicate_main.sui b/tests/import_tests/duplicate_main.sui
new file mode 100644
index 0000000..ad4a6ab
--- /dev/null
+++ b/tests/import_tests/duplicate_main.sui
@@ -0,0 +1,6 @@
+use "./module_a"
+use "./module_b"
+
+fn main() -> int do
+  0
+end
diff --git a/tests/import_tests/good_import.c b/tests/import_tests/good_import.c
new file mode 100644
index 0000000..556be3d
--- /dev/null
+++ b/tests/import_tests/good_import.c
@@ -0,0 +1,20 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+struct Point {
+    int x;
+    int y;
+};
+int helper_func(void);
+int main(void);
+
+
+int helper_func(void) {
+    return 42;
+}
+
+int main(void) {
+    return helper_func();
+}
+
diff --git a/tests/import_tests/good_import.sui b/tests/import_tests/good_import.sui
new file mode 100644
index 0000000..74a48ad
--- /dev/null
+++ b/tests/import_tests/good_import.sui
@@ -0,0 +1,5 @@
+use "./util"
+
+fn main() -> int do
+  helper_func()
+end
diff --git a/tests/import_tests/module_a.sui b/tests/import_tests/module_a.sui
new file mode 100644
index 0000000..9ee28c9
--- /dev/null
+++ b/tests/import_tests/module_a.sui
@@ -0,0 +1,3 @@
+fn test_func() -> int do
+  42
+end
diff --git a/tests/import_tests/module_b.sui b/tests/import_tests/module_b.sui
new file mode 100644
index 0000000..850a737
--- /dev/null
+++ b/tests/import_tests/module_b.sui
@@ -0,0 +1,3 @@
+fn test_func() -> int do
+  99
+end
diff --git a/tests/import_tests/util.sui b/tests/import_tests/util.sui
new file mode 100644
index 0000000..47bd1bd
--- /dev/null
+++ b/tests/import_tests/util.sui
@@ -0,0 +1,8 @@
+fn helper_func() -> int do
+  42
+end
+
+struct Point
+    x: int,
+    y: int,
+end