Research has suggested that lonely people demonstrate distinct differences from nonlonely people in their behaviors, mood, and interpersonal experiences. Lonely people who are also enduring a chronic pain condition may be at an especially high risk for negative outcomes because of simultaneous issues such as stigma, mood disturbances, and pain-related disability. The current study examined chronic and transitory loneliness in a sample of 123 chronic pain patients. Participants completed daily diaries assessing the occurrence of positive and negative interpersonal events, appraisals of interpersonal events, pain, and mood. Multilevel modeling was used to examine effects of being a lonely person as well as having a lonely episode on daily life. Results indicated that both chronic and transitory loneliness were associated with more frequent negative and less frequent positive interpersonal events, higher levels of pain, more negative and less positive affect, and more stress and less enjoyment from social interactions. Loneliness did not affect reactivity to negative interpersonal events, but did influence responsivity to positive interpersonal events such that lonely people had greater boosts in enjoyment when experiencing more positive interpersonal events than usual. These findings suggest that both lonely people and individuals experiencing a lonely episode experience more negative consequences in their daily lives than nonlonely people. However, they can benefit from engaging in more frequent positive interpersonal events, which can help to inform future clinical interventions for lonely, chronic pain patients.