Social experiences are of great importance in late life, and the need to belong may play a key role in shaping those experiences. A higher need to belong may motivate older adults to maintain a wide variety of social connections (e.g., family ties, friends, acquaintances, group engagement), yet may also lead to higher risks of feeling unsatisfied and lonely. However, little research examines how the need to belong may shape older adults’ social life in the daily context. This study examines the associations between older adults’ need to belong, daily social engagement, and transient loneliness in their everyday life. Older adults ( N = 299) aged 65–89 completed the Need to Belong Scale, measures of their social networks, and ecological momentary assessment (EMA) surveys for five to six days. At each three-hour assessment, they reported in-person and phone contact with a variety of social partners (e.g., family, friends, acquaintances, etc.), whether they engaged in a social group, and rated their feelings of loneliness. In multilevel models, the need to belong did not predict the variety of partners encountered in-person or by phone, but predicted a greater likelihood of engagement with social groups. Older adults with a higher need to belong reported that they felt lonelier at three-hour intervals throughout the day, but this association was attenuated when they had in-person encounters with a greater variety of social partners. Group engagement was associated with feeling less lonely, whereas phone communication was associated with feeling more lonely, regardless of the need to belong. The findings suggest that social engagement with a variety of types of social partners may help satisfy older adults’ need to belong, and highlight the unique benefits that in-person contact (vs. phone contact) and group engagement may confer to mitigate older adults’ loneliness.