Mobile application stores have revolutionised the dynamics of mobile ecosystems. Research onmobile application ecosystems has been significantly driven by data that is focused on the visualisation of an ecosystem's dynamics. This is a valuable step towards understanding the nature of the ecosystems, but it is limited in its explanatory power. Thus, a theory-driven approach is needed to understand the overall dynamics of such systems. This study applies a theoretical framework of value creation in e-business in the context of mobile application ecosystems, with a focus on application developers. A qualitative research strategy is employed in testing operationalisationina sample of developers. The sample comprises 27 application developers from the three leading mobile application ecosystems. The results show that efficiency is the main source of value, products seldom create value through complementarities, and approaches towards lock-in and novelty seem to vary among application developers. The managerial and theoretical implications of such biased value creation in mobile ecosystems are considered.