1. A new method of observation is used to assay the behavior of three groups of individuals from colonies ofLasioglossum zephyrum (Hymenoptera: Halictidae). These groups (queens, guards, and foragers) differ significantly in several behavioral attributes. Guards were never observed to pass non-nestmate guards, a common interaction among nestmates. Foragers and queens pass frequently. Guards elicit submissive behavior from foragers more frequently than foragers elicit submissive behavior in guards. 2. Queens are significantly larger in two body size measurements than guards, and guards are significantly larger than foragers. Queens have the largest ovaries, guards the second largest, and foragers the smallest, on the average. 3. A relationship between ovarian development and dominance behavior is suggested but not conclusively demonstrated. 4. Young (1 day old) bees with no social experience engage in normal social interactions, including passing, but older (5 day old) inexperienced bees do not pass; there is apparently a critical period in the behavioral development of individuals after which the cannot engage in normal social interactions. 5. In encounters between members of different groups individuals can rapidly assess the status of the individual which they are encountering and display the appropriate behavioral response.