Individual-level inertia exists if users stick to incumbent technologies even if better alternatives are available. Thus, inertial behavior fosters the continued use of current information systems rather than the adoption of new ones. Despite the growing research interest in inertia in recent years and its importance for users’ post-adoption decisions, there is still no common ground or procedure to examine these psychological effects. Foremost, although there is strong theoretical proximity, inertia is still neglected in established continuance and switching models. To close this research gap and to provide a consolidated basis for future research, we integrate inertia into both UTAUT2 and the PPM framework and investigate their adequacy empirically. We find that PPM exhibits higher overall goodness-of-fit, while UTAUT2 is more appropriate for inertia integration concerning reliability criteria and explanatory power. We further derive recommendations on adapting UTAUT2 to continuance contexts and on conceptualizing inertia for different research approaches.