We conducted a representative survey of Mogadishu's population—the first in 25 years—in March 2012. We overcame challenges related to lack of data and poor security with the use of remote sensing, the systematic development of local contacts through the Somali diaspora, the flexible deployment of staff, and mobile technology. This article demonstrates the value of using transparent sampling methods to produce reliable estimates for humanitarian response and policy makers. The article also highlights shortcomings and lessons learned from our approach, with the goal of improving future data collection efforts in insecure environments.