Kai Spohrer, Monica Fallon, Hartmut Höhle, and Armin Heinzl Armin Heinzl have successfully published their research on designing effective mobile health apps in the FT50 outlet “Journal of Management Information Systems.” The authors conducted explanatory design science research to theorize and empirically examine if and why combinations of multiple behavior change techniques in mobile health apps (mHealth) do not necessarily result in synergistic effects. Drawing on theories of protection motivation and social upward comparison, the researchers developed and evaluated four mHealth prototypes for stress alleviation. The results of a five-week field experiment with n=138 participants and a subsequent qualitative substantiation show that there is a negative interaction effect of protection motivation and social upward comparison, rendering their combined application less effective. The research elicits mutual boundary conditions for theories of protection motivation and social upward comparison. If mechanisms of one theory are present, they restrict the effectiveness of mechanisms of the other theory. The paper shows that developers of mHealth apps need to be extremely careful when implementing and combining features that originate from different behavior change theories. Some combinations are actually detrimental to the positive behavior change they are intended to generate.