Interactions between clouds, aerosols, and precipitation and the resulting impacts on the global energy and water cycle represent a critical pathway by which human activities can impact the global climate system. Yet aerosol indirect effects are among the least well understood and most hotly debated processes in current climate research. Due to their strong sensitivity to both aerosol composition and the local environment, understanding and ultimately quantifying aerosol-cloud interactions on global scales requires an interdisciplinary approach that includes analysis of multi-sensor datasets and associated modeling activities to establish causality and investigate underlying physical processes.