Maine has thousands of lakes, and all are unique. However, many lakes share traits that help lake managers, watershed organizations, and researchers compare and evaluate them. This is especially important for lake assessments, which often compare a lake’s condition to the condition of reference lakes from minimally-disturbed watersheds. By determining which natural attributes of lakes and their watersheds have the strongest influence on lake condition, we can place lakes into categories that define what the conditions of certain types of lakes should be. These categories will help managers place lake data in the proper context for better evaluation and planning. This talk will be about how lake types were developed for Maine lakes, and how these types may be applied to lake assessment and protection.