diff --git a/lib/wavesync/cli.rb b/lib/wavesync/cli.rb
index 58ea3b2..7f0b759 100644
--- a/lib/wavesync/cli.rb
+++ b/lib/wavesync/cli.rb
@@ -42,7 +42,7 @@ def self.start_sync
       parser.parse!
 
       config_path = options[:config] || Wavesync::Config::DEFAULT_PATH
-      config = Wavesync::Config.load(config_path)
+      config = load_config(config_path)
 
       device_configs = config.device_configs
       if options[:device]
@@ -85,7 +85,7 @@ def self.start_set
       parser.parse!
 
       config_path = options[:config] || Wavesync::Config::DEFAULT_PATH
-      config = Wavesync::Config.load(config_path)
+      config = load_config(config_path)
 
       case subcommand
       when 'create'
@@ -118,6 +118,13 @@ def self.start_set
       end
     end
 
+    def self.load_config(path)
+      Wavesync::Config.load(path)
+    rescue Wavesync::ConfigError => e
+      puts "Configuration error: #{e.message}"
+      exit 1
+    end
+
     def self.require_set_name(subcommand)
       name = ARGV.shift
       unless name
@@ -144,7 +151,7 @@ def self.start_analyze
       parser.parse!
 
       config_path = options[:config] || Wavesync::Config::DEFAULT_PATH
-      config = Wavesync::Config.load(config_path)
+      config = load_config(config_path)
 
       Wavesync::Analyzer.new(config.library).analyze(overwrite: options[:overwrite] || false)
     end
diff --git a/lib/wavesync/config.rb b/lib/wavesync/config.rb
index 2c01fad..bd01cae 100644
--- a/lib/wavesync/config.rb
+++ b/lib/wavesync/config.rb
@@ -3,21 +3,68 @@
 require 'yaml'
 
 module Wavesync
+  class ConfigError < StandardError; end
+
   class Config
     DEFAULT_PATH = File.join(Dir.home, 'wavesync.yml')
 
+    SUPPORTED_KEYS = %w[library devices].freeze
+    DEVICE_SUPPORTED_KEYS = %w[name model path].freeze
+    DEVICE_REQUIRED_KEYS = %w[name model path].freeze
+
     attr_reader :library, :device_configs
 
     def self.load(path = DEFAULT_PATH)
-      data = YAML.load_file(File.expand_path(path))
+      expanded = File.expand_path(path)
+      begin
+        data = YAML.load_file(expanded)
+      rescue Errno::ENOENT
+        raise ConfigError, "Config file not found: #{path}"
+      rescue Psych::SyntaxError => e
+        raise ConfigError, "Invalid YAML in config file: #{e.message}"
+      end
       new(data)
     end
 
     def initialize(data)
-      @library = File.expand_path(data.fetch('library'))
-      @device_configs = data.fetch('devices').map do |device|
+      validate!(data)
+      @library = File.expand_path(data['library'])
+      @device_configs = data['devices'].each_with_index.map do |device, i|
+        validate_device!(device, i)
         { name: device['name'], model: device['model'], path: File.expand_path(device['path']) }
       end
     end
+
+    private
+
+    def validate!(data)
+      raise ConfigError, 'Config file must contain a YAML mapping' unless data.is_a?(Hash)
+
+      unsupported = data.keys - SUPPORTED_KEYS
+      raise ConfigError, "Unsupported config keys: #{unsupported.join(', ')}" if unsupported.any?
+
+      %w[library devices].each do |key|
+        raise ConfigError, "Missing required config key: '#{key}'" unless data.key?(key)
+      end
+
+      raise ConfigError, "'library' must be a string" unless data['library'].is_a?(String)
+      raise ConfigError, "'devices' must be a list" unless data['devices'].is_a?(Array)
+      raise ConfigError, "'devices' must contain at least one device" if data['devices'].empty?
+    end
+
+    def validate_device!(device, index)
+      raise ConfigError, "Device #{index + 1} must be a YAML mapping" unless device.is_a?(Hash)
+
+      unsupported = device.keys - DEVICE_SUPPORTED_KEYS
+      raise ConfigError, "Unsupported keys in device #{index + 1}: #{unsupported.join(', ')}" if unsupported.any?
+
+      DEVICE_REQUIRED_KEYS.each do |key|
+        raise ConfigError, "Missing required key '#{key}' in device #{index + 1}" unless device.key?(key)
+      end
+
+      %w[name model path].each do |key|
+        raise ConfigError, "Device #{index + 1} '#{key}' must be a string" unless device[key].is_a?(String)
+      end
+    end
   end
 end
diff --git a/test/wavesync/config_test.rb b/test/wavesync/config_test.rb
new file mode 100644
index 0000000..af46dd2
--- /dev/null
+++ b/test/wavesync/config_test.rb
@@ -0,0 +1,170 @@
+# frozen_string_literal: true
+
+require 'tempfile'
+require_relative 'test_case'
+require_relative '../../lib/wavesync/config'
+
+module Wavesync
+  class ConfigTest < Wavesync::TestCase
+    VALID_CONFIG = {
+      'library' => '/tmp/library',
+      'devices' => [
+        { 'name' => 'My Device', 'model' => 'TP-7', 'path' => '/tmp/device' }
+      ]
+    }.freeze
+
+    test 'load raises ConfigError when file does not exist' do
+      error = assert_raises(ConfigError) { Config.load('/nonexistent/path/wavesync.yml') }
+      assert_match 'Config file not found', error.message
+    end
+
+    test 'load raises ConfigError for malformed YAML' do
+      file = Tempfile.new(['wavesync', '.yml'])
+      file.write("library: /tmp\ndevices: [\nbad yaml{{")
+      file.close
+      error = assert_raises(ConfigError) { Config.load(file.path) }
+      assert_match 'Invalid YAML in config file', error.message
+    ensure
+      file.unlink
+    end
+
+    test 'load succeeds with valid config file' do
+      file = Tempfile.new(['wavesync', '.yml'])
+      file.write("library: /tmp\ndevices:\n  - name: My Device\n    model: TP-7\n    path: /tmp/device\n")
+      file.close
+      config = Config.load(file.path)
+      assert_equal File.expand_path('/tmp'), config.library
+    ensure
+      file.unlink
+    end
+
+    test 'raises ConfigError when YAML root is not a hash' do
+      error = assert_raises(ConfigError) { Config.new(['not', 'a', 'hash']) }
+      assert_match 'must contain a YAML mapping', error.message
+    end
+
+    test 'raises ConfigError when YAML root is nil' do
+      error = assert_raises(ConfigError) { Config.new(nil) }
+      assert_match 'must contain a YAML mapping', error.message
+    end
+
+    test 'raises ConfigError for unsupported top-level keys' do
+      data = VALID_CONFIG.merge('unknown_key' => 'value')
+      error = assert_raises(ConfigError) { Config.new(data) }
+      assert_match 'Unsupported config keys', error.message
+      assert_match 'unknown_key', error.message
+    end
+
+    test 'raises ConfigError when library key is missing' do
+      data = VALID_CONFIG.reject { |k, _| k == 'library' }
+      error = assert_raises(ConfigError) { Config.new(data) }
+      assert_match "Missing required config key: 'library'", error.message
+    end
+
+    test 'raises ConfigError when devices key is missing' do
+      data = VALID_CONFIG.reject { |k, _| k == 'devices' }
+      error = assert_raises(ConfigError) { Config.new(data) }
+      assert_match "Missing required config key: 'devices'", error.message
+    end
+
+    test 'raises ConfigError when library is not a string' do
+      data = VALID_CONFIG.merge('library' => ['not', 'a', 'string'])
+      error = assert_raises(ConfigError) { Config.new(data) }
+      assert_match "'library' must be a string", error.message
+    end
+
+    test 'raises ConfigError when devices is not an array' do
+      data = VALID_CONFIG.merge('devices' => 'not an array')
+      error = assert_raises(ConfigError) { Config.new(data) }
+      assert_match "'devices' must be a list", error.message
+    end
+
+    test 'raises ConfigError when devices is empty' do
+      data = VALID_CONFIG.merge('devices' => [])
+      error = assert_raises(ConfigError) { Config.new(data) }
+      assert_match "'devices' must contain at least one device", error.message
+    end
+
+    test 'raises ConfigError when a device entry is not a hash' do
+      data = VALID_CONFIG.merge('devices' => ['not a hash'])
+      error = assert_raises(ConfigError) { Config.new(data) }
+      assert_match 'Device 1 must be a YAML mapping', error.message
+    end
+
+    test 'raises ConfigError for unsupported device keys' do
+      device = { 'name' => 'My Device', 'model' => 'TP-7', 'path' => '/tmp', 'extra' => 'bad' }
+      data = VALID_CONFIG.merge('devices' => [device])
+      error = assert_raises(ConfigError) { Config.new(data) }
+      assert_match 'Unsupported keys in device 1', error.message
+      assert_match 'extra', error.message
+    end
+
+    test 'raises ConfigError when device name is missing' do
+      device = { 'model' => 'TP-7', 'path' => '/tmp' }
+      data = VALID_CONFIG.merge('devices' => [device])
+      error = assert_raises(ConfigError) { Config.new(data) }
+      assert_match "Missing required key 'name' in device 1", error.message
+    end
+
+    test 'raises ConfigError when device model is missing' do
+      device = { 'name' => 'My Device', 'path' => '/tmp' }
+      data = VALID_CONFIG.merge('devices' => [device])
+      error = assert_raises(ConfigError) { Config.new(data) }
+      assert_match "Missing required key 'model' in device 1", error.message
+    end
+
+    test 'raises ConfigError when device path is missing' do
+      device = { 'name' => 'My Device', 'model' => 'TP-7' }
+      data = VALID_CONFIG.merge('devices' => [device])
+      error = assert_raises(ConfigError) { Config.new(data) }
+      assert_match "Missing required key 'path' in device 1", error.message
+    end
+
+    test 'raises ConfigError when device name is not a string' do
+      device = { 'name' => 123, 'model' => 'TP-7', 'path' => '/tmp' }
+      data = VALID_CONFIG.merge('devices' => [device])
+      error = assert_raises(ConfigError) { Config.new(data) }
+      assert_match "Device 1 'name' must be a string", error.message
+    end
+
+    test 'raises ConfigError when device model is not a string' do
+      device = { 'name' => 'My Device', 'model' => ['TP-7'], 'path' => '/tmp' }
+      data = VALID_CONFIG.merge('devices' => [device])
+      error = assert_raises(ConfigError) { Config.new(data) }
+      assert_match "Device 1 'model' must be a string", error.message
+    end
+
+    test 'raises ConfigError when device path is not a string' do
+      device = { 'name' => 'My Device', 'model' => 'TP-7', 'path' => { 'bad' => 'type' } }
+      data = VALID_CONFIG.merge('devices' => [device])
+      error = assert_raises(ConfigError) { Config.new(data) }
+      assert_match "Device 1 'path' must be a string", error.message
+    end
+
+    test 'error message references correct device index for second device' do
+      valid_device = { 'name' => 'First', 'model' => 'TP-7', 'path' => '/tmp' }
+      bad_device = { 'name' => 'Second', 'model' => 'TP-7' }
+      data = VALID_CONFIG.merge('devices' => [valid_device, bad_device])
+      error = assert_raises(ConfigError) { Config.new(data) }
+      assert_match 'device 2', error.message
+    end
+
+    test 'initializes with valid data' do
+      config = Config.new(VALID_CONFIG)
+      assert_equal File.expand_path('/tmp/library'), config.library
+      assert_equal 1, config.device_configs.size
+      assert_equal 'My Device', config.device_configs.first[:name]
+      assert_equal 'TP-7', config.device_configs.first[:model]
+      assert_equal File.expand_path('/tmp/device'), config.device_configs.first[:path]
+    end
+
+    test 'initializes with multiple devices' do
+      data = VALID_CONFIG.merge('devices' => [
+                                  { 'name' => 'Device A', 'model' => 'TP-7', 'path' => '/tmp/a' },
+                                  { 'name' => 'Device B', 'model' => 'Octatrack', 'path' => '/tmp/b' }
+                                ])
+      config = Config.new(data)
+      assert_equal 2, config.device_configs.size
+    end
+  end
+end