A good deal of research has recently been directed at analyzing the relationship between population density and the perception of crowding. This research was reviewed by outlining the variables that have been shown to increase (input overload, behavioral interference, and personal space violations) and decrease (activity and termination control) the perception of crowding. It was then proposed that affective variables, as well as cognitive and behavioral variables, have a significant influence on the perception of crowding. In order to test for the effects of affective and cognitive variables on the perception of crowding, a short-term high density laboratory experiment was conducted. In this experiment, individuals in all-male, all-female, or mixed-sex groups, were exposed to a positive, neutral or negative mood-inducing film. In addition, half of the participants were given perceived control over the experience, while the remainder were given no such information. It was predicted that a positive mood-inducer would decrease perception of crowding and a negative mood-inducer would increase the perception of crowding for individuals in a high density setting. The results only partially support this prediction. Positive mood decreased perception of crowding, but only for individuals in mixed-sex groups. Mood variations had no other reliable effects on the perception of crowding. It was also predicted that individuals with perceived control would report feeling less crowded than individuals without control. This prediction was supported in only the most limited conditions. Individuals in all-women groups, sitting in middle seats, and with perceived control reported feeling less crowded than did comparable individuals without perceived control. It was also predicted that mood and perceived control would interact to affect the perception of crowding. The results failed to support this prediction. A variety of theoretical and methodological explanations for these results were examined. It was concluded that mood variations, heretofore ignored in the literature, can influence the perception of crowding, especially when stemming directly from the high density experience. Conclusions about the effect of perceived control on the perception of crowding (commonly accepted in the current literature) should be re-examined before general acceptance.