Abstract: This invention generally relates to apparatus and methods for attaching a rail and a post. More particularly, the invention relates to novel brackets for attaching horizontal or diagonal rails to vertical posts. The bracket is fastened to the post and is inserted in an open end of a rail, and the rail is fastened to the bracket, including at various angles relative to the post. The present invention includes methods of attaching a rail to a post, railing systems comprising a rail fastened to a post, and kits including one or more brackets.