In this article, the authors focused on findings from qualitative research on the effects of action research by reporting two linked quantitative studies. The authors' first goal was to triangulate the findings from their quantitative inquiry with the results from qualitative studies in order to increase the generalizability of claims previously reported. Their second goal was to identify potential moderators of action research impact on teachers. The contribution of these two studies to the corpus of action research literature is twofold. First, the authors confirmed two important benefits of action research participation reported by qualitative researchers, improved teacher attitudes to educational research and increased self-efficacy. Second, they found moderators of the impact of action research that help identify conditions in which action research is particularly likely to benefit teachers.