Technical advances in mosquito biology are enabling the development of new approaches to vector control. Absent are powerful forward-genetics technologies, such as enhancer and gene traps, that permit determination of gene functions from the phenotypes arising from transposon insertion mutations. We show that the piggyBac transposon is highly active in the germline of the human malaria vector Anopheles stephensi. Up to 6% of the progeny from transgenic A. stephensi containing a single 6-kb piggyBac element with a marker gene expressing EGFP had the vector in new genomic locations when piggyBac transposase was provided in trans from a second integrated transgene. The active transposition of piggyBac resulted in the efficient detection of enhancers, with ~10% of the progeny with piggyBac in new locations with novel patterns of EGFP expression in third and fourth instar larvae and in adults. The availability of advanced transgenic capabilities such as efficient transposon-based forward-genetics technologies for Anopheles mosquitoes not only will accelerate our understanding of mosquito functional genomics and the development of novel vector and disease transmission control strategies, but also will enable studies by evolutionary developmental biologists, virologists, and parasitologists.