Mixed methods were used to model a system to explain why an elaborate innovation succeeded and grew in three cases but was discontinued in a fourth. In addition to comparing the outcomes, the explanatory models were also mapped onto the original program theory. The result of the comparisons across the post-hoc models, and also between the models and the original program theory, yielded powerful information to guide policy and practice. For more information contact any of the authors. Jonny Morell jmorell@fulcrum-corp.com, Joyce Ranney Joyce.Ranney@dot.gov, Melinda Davey Melinda.Davey@jacobs.com, or Tom Raslear thomas.raslear@dot.gov.