Peace operations now conduct a wide range of different missions, but much of the scholarship has focused only on one mission at a time, and most often this is the task of monitoring cease-fires. This article draws attention to the phenomena of multiple missions within peace operations, and discusses some of the hurdles to understanding how such missions influence one another. We begin by providing a descriptive analysis of 11 different peace missions carried out by UN operations over the 1948–2015 period. Following a review of multiple-mission studies to date, we call attention to several problems with approaches taken for understanding peacekeeping outcomes. We then elucidate seven considerations or challenges in understanding how missions interact with one another and influence each other’s success, providing guidelines for how to analyse them.