Mobile technologies are promising tools to scaffold teaching practice. In this study, we developed and tested a mobile app for teacher education. This mobile portfolio enables multimedia-based note-taking, reflection, and discussion with peers and mentors. We conducted two studies to explore the effect of design variants and use scenarios on the app's acceptance. In the first study with N = 83 pre-service primary school teachers, technology acceptance was higher for those using the app with multimedia note-taking functionality than for those using the same app with this functionality disabled. In the second study with N = 81 pre-service teachers, those using the app together with their mentor teachers reported levels of technology acceptance similar to those who used the app exclusively among themselves. In consequence, a mobile portfolio app would be met with higher acceptance if it builds reflection upon multimedia note-taking both with and without the inclusion of mentors.