Modern graphical user interfaces support direct manipulation of objects and object groups. Current object group selection techniques such as lasso and rectangle selection can be time-consuming and error-prone. This paper presents a new approach to group selection that exploits the way human perception naturally groups objects, also known as Gestalt grouping. Based on known results from perception research, we present a novel method to group objects via models of the Gestalt principles of proximity and (curvi-)linearity. Then, we introduce several new mouse-based selection techniques that exploit these Gestalt groups. The results of a user study show that our new technique outperforms lasso and rectangle selection for object groups with an implicit structure, such as (curvi-)linear arrangements or clusters.