Many types of multi-display environments (MDEs) are emerging that allow users to better interact with computers. In these environments, being able to move visual objects (such as window icons or the cursor) from one display to another is a fundamental activity. This dissertation focuses on understanding how human performance of cross-display actions is affected by the design of cross-display object movement interaction techniques. Three main aspects of cross-display actions are studied: how displays are referred to by the system and the users, how spatial actions are planned, and how actions are executed. Each of these three aspects is analyzed through laboratory experiments that provide empirical evidence on how different characteristics of interaction techniques affect performance. The results further our understanding of cross-display interaction and can be used by designers of new MDEs to create more efficient multi-display interfaces.