The W.K. Kellogg Foundation Logic Model Development Guide, a companion publication to the Evaluation Handbook, focuses on the development and use of the program logic model. We have found the logic model and its processes facilitate thinking, planning, and communications about program objectives and actual accomplishments. Through this guide, we hope to provide an orientation to the underlying principles and language of the program logic model so it can be effectively used in program planning, implementation, and dissemination of results.