The presentation focuses on the study implemented in Bangladesh to identify dissemination and catchment areas of the Genetically Improved Farmed Tilapia (GIFT) in Bangladesh. In the study, we surveyed tilapia hatchers and farmers and showed that information provided by hatchers closely matched that provided by farmers. We demonstrate how “catchment areas” for an innovation disseminated over a long period of time, such as GIFT, can be identified and show that there exist enough tilapia farmers (both GIFT and non-GIFT) to allow an adequately powered impact evaluation for GIFT in Bangladesh. Our ability to validate the catchment areas for GIFT and non-GIFT farmers suggests the possibility to construct a counterfactual for evaluation of impacts of GIFT.