While debates continue about the rigor and relevance of IS research, theories are still widely accepted as the bedrock of scientific research. This paper addresses the issues surrounding academic research rigor and relevance by discussing the rigor and relevance of research theories--in particular, big T and little t theories. Big T theories are usually highly recognized, refined, validated, and generalizable theories usually associated with rigorous research and publication. Little t theories may be relatively immature, little known, narrowly focused, simple, and highly relevant theories more generally appreciated by business practitioners. Little t theories have special characteristics that can be very useful to researchers and teachers, and highly relevant to business practitioners. Moreover, academics can take clear steps to build, publish, teach, and apply little t theories.