Poster presentation 279: Evaluation 2015 -- We look at the challenges and benefits of creating and using a fully articulated program theory model from the perspective of the PI and program stakeholders and from the external evaluator. We use the term "program theory model" to reflect a model that goes beyond the inputs and outputs of a simple logic model, that incorporates the context (and partners) in which the program operates and where a theory of change model is explicitly embedded. What are some of the challenges in the development of a program theory model? What factors might be needed to help insure that the program theory model is use? How does a program theory model evolve from a requirement at the proposal development stage to become a live document that is useful and used by both program stakeholders and the external evaluator? We present select factors that we see as key to this process.#ProgramTheoryandTheoryDrivenEvaluation #PosterPresentationatEvaluation2015