Actionable recommendation from Counterintuitive Rails pt. 1: rather than keeping a flat app/models, group models into folders based on entity dependencies (loosely related to DDD aggregate roots). If Comment and Link don't make sense without Article, put them under article/ and rename to Article::Comment and Article::Link. Do it from day one — retrofitting forces dealing with renames. Rails fully supports the namespace; at worst, specify class_name on the parent.