Objective: Changes in surroundings and social relationships may heighten feelings of loneliness, suggesting the need to measure as a state. This study tested whether loneliness fluctuates within and across days and the resultant associations with psychological distress. Further it tested familism as a moderator as endorsing this cultural value may buffer the negative effects of state loneliness. Participants: Participants (n = 220) were Latinx undergraduate students. Methods: Students reported their loneliness levels and psychological distress twice a day for two weeks using an ecological momentary assessment approach. Results: Results showed that experiencing a higher than usual level of loneliness predicted greater sadness, stress, and anxiety at both the moment-to-moment and day-to-day level. Familism, measured at baseline, only moderated the relationship between loneliness and sadness. Conclusions: The findings suggest being in a lonely moment may lead to the initiation or amplification of psychological distress immediately and the effects may linger over the day.