In this research, we showed that solitude generally has a deactivation effect on people’s affective experiences, decreasing both positive and negative high-arousal affects. In Study 1, we found that the deactivation effect occurred when people were alone, but not when they were with another person. Study 2 showed that this deactivation effect did not depend on whether or not the person was engaged in an activity such as reading when alone. In Study 3, high-arousal positive affect did not drop in a solitude condition in which participants specifically engaged in positive thinking or when they actively chose what to think about. Finally, in Study 4, we found that solitude could lead to relaxation and reduced stress when individuals actively chose to be alone. This research thus shed light on solitude effects in the past literature, and on people’s experiences when alone and the different factors that moderate these effects.