In this chapter, we conduct a meta-analysis of breakoff rates in mobile web surveys. We test whether the optimization of web surveys for mobile devices, invitation mode (SMS vs. email), survey length, expected duration stated in the survey invitation, survey design (scrolling vs. paging), prerecruitment, number of reminders, design complexity (grids, drop-down questions, sliders, images, progress indicator), incentives, opportunity to skip survey questions, and opportunity to select the preferred mode (PC or mobile web) have an effect on breakoffs. The meta-analysis is based on 14 studies (39 independent samples) conducted using online panels – probability-based and non-probability-based. We found that mobile optimized surveys, email invitations, shorter surveys, using prerecruitment, more reminders, a less complex design, and an opportunity to choose the preferred survey mode all decrease breakoff rates in mobile web surveys. No effect of a scrolling design, incentives, indicating expected duration in the invitation, and letting an opportunity to skip survey questions was found.