diff --git a/depnav/src/depnav/config.py b/depnav/src/depnav/config.py
new file mode 100644
index 0000000..b14c887
--- /dev/null
+++ b/depnav/src/depnav/config.py
@@ -0,0 +1,162 @@
+"""Configuration management for depnav."""
+
+import os
+from pathlib import Path
+from typing import Any, Optional, Tuple, Union
+
+import yaml
+
+
+class Config:
+    """Configuration manager for depnav."""
+
+    DEFAULT_CONFIG_NAMES = [".depnav.yaml", "depnav.yaml", "pyproject.toml"]
+    DEFAULT_DEPTH = 3
+    DEFAULT_MAX_NODES = 100
+
+    def __init__(self, config_path: Optional[Path] = None):
+        self._config: dict[str, Any] = {}
+        self._config_path = config_path
+
+    def load(self) -> None:
+        """Load configuration from file and environment."""
+        self._config = {}
+
+        if self._config_path and self._config_path.exists():
+            self._load_from_file(self._config_path)
+        else:
+            self._find_and_load_config()
+
+        self._apply_env_overrides()
+
+    def _find_and_load_config(self) -> None:
+        """Find and load configuration from standard locations."""
+        for config_name in self.DEFAULT_CONFIG_NAMES:
+            config_path = Path.cwd() / config_name
+            if config_path.exists():
+                self._load_from_file(config_path)
+                break
+
+    def _load_from_file(self, path: Path) -> None:
+        """Load configuration from a YAML or TOML file."""
+        try:
+            content = path.read_text()
+            ext = path.suffix.lower()
+
+            if ext == ".toml":
+                try:
+                    import tomli
+                    data = tomli.loads(content) or {}
+                except ImportError:
+                    try:
+                        import tomllib
+                        data = tomllib.loads(content) or {}
+                    except ImportError:
+                        data = {}
+
+                if path.name == "pyproject.toml":
+                    data = data.get("tool", {}).get("depnav", {})
+            else:
+                data = yaml.safe_load(content) or {}
+
+            self._config.update(data)
+        except (yaml.YAMLError, OSError):
+            pass
+
+    def _apply_env_overrides(self) -> None:
+        """Apply environment variable overrides."""
+        env_map: dict[str, Tuple[str, Optional[int]]] = {
+            "DEPNAV_CONFIG": ("config_file", None),
+            "DEPNAV_THEME": ("theme", None),
+            "DEPNAV_PAGER": ("pager", None),
+            "DEPNAV_DEPTH": ("depth", self.DEFAULT_DEPTH),
+            "DEPNAV_MAX_NODES": ("max_nodes", self.DEFAULT_MAX_NODES),
+        }
+
+        for env_var, (key, default) in env_map.items():
+            env_value = os.environ.get(env_var)
+            if env_value is not None:
+                value: Union[int, str] = env_value
+                if default is not None and isinstance(default, int):
+                    value = int(env_value)
+                self._config[key] = value
+
+    def get(self, key: str, default: Any = None) -> Any:
+        """Get a configuration value."""
+        return self._config.get(key, default)
+
+    def get_theme(self) -> dict[str, Any]:
+        """Get the current theme configuration."""
+        themes = self._config.get("themes", {})
+        theme_name = self._config.get("theme", "default")
+        return themes.get(theme_name, themes.get("default", self._default_theme()))
+
+    def _default_theme(self) -> dict[str, Any]:
+        """Return the default theme configuration."""
+        return {
+            "node_style": "cyan",
+            "edge_style": "dim",
+            "highlight_style": "yellow",
+            "cycle_style": "red",
+        }
+
+    def get_exclude_patterns(self) -> list[str]:
+        """Get patterns for excluding files/directories."""
+        return self._config.get("exclude", ["__pycache__", "node_modules", ".git"])
+
+    def get_include_extensions(self) -> list[str]:
+        """Get file extensions to include."""
+        return self._config.get(
+            "extensions", [".py", ".js", ".jsx", ".ts", ".tsx", ".go"]
+        )
+
+    def get_output_format(self) -> str:
+        """Get the default output format."""
+        return self._config.get("output", "ascii")
+
+    def get_depth(self) -> int:
+        """Get the default traversal depth."""
+        return int(self._config.get("depth", self.DEFAULT_DEPTH))
+
+    def get_max_nodes(self) -> int:
+        """Get the maximum number of nodes to display."""
+        return int(self._config.get("max_nodes", self.DEFAULT_MAX_NODES))
+
+    def save(self, path: Path) -> None:
+        """Save current configuration to a file."""
+        with open(path, "w") as f:
+            yaml.dump(self._config, f, default_flow_style=False)
+
+    def set(self, key: str, value: Any) -> None:
+        """Set a configuration value."""
+        self._config[key] = value
+
+    def merge(self, other: dict[str, Any]) -> None:
+        """Merge another configuration dictionary."""
+        self._config.update(other)
+
+    def __repr__(self) -> str:
+        return f"Config({self._config})"
+
+
+def load_config(config_path: Optional[Path] = None) -> Config:
+    """Load and return a configuration object."""
+    config = Config(config_path)
+    config.load()
+    return config
+
+
+def get_config_value(
+    key: str, default: Any = None, config: Optional[Config] = None
+) -> Any:
+    """Get a configuration value from a config or environment."""
+    if config is not None:
+        return config.get(key, default)
+
+    env_key = f"DEPNAV_{key.upper()}"
+    env_value = os.environ.get(env_key)
+    if env_value is not None:
+        return env_value
+
+    cfg = load_config()
+    return cfg.get(key, default)