Appreciation of Social Experiences and Solitude in Everyday Life: The SOcial Experiences' daiLy Occurrence Scale (SOLO).

While social interactions and actively chosen solitude both contribute to well-being, existing measures focus solely on one dimension. We developed the SOcial experiences' daiLy Occurrence (SOLO) scale-a brief end-of-day diary measure capturing enjoyment of social interactions (including brief encounters with "weak ties") and solitude experiences. Two scale development and validation studies were conducted: single-day (N = 203) and 14-day (N = 75) assessments. The final SOLO consists of 13 items forming two scales, the Social Interaction subscale and the Solitude subscale. Both scales demonstrated adequate psychometric properties and meaningful relationships with well-being measures. The scales were independent, supporting the conceptualization of social enjoyment and solitude preference as distinct dimensions. The SOLO is therefore presented as two distinct scales. A composite score can be calculated if required, although subscale-level analyses are recommended given the empirical independence of the two dimensions. The SOLO's brief format offers a practical compromise between ecological momentary assessment and retrospective measures, enabling investigation of the distinct roles of social engagement and solitude in everyday life.