Development and Validation of the Engaging in Life Scale: Long and Short Forms among Chinese Adults with Emotional Distress

Engaging in life has been proposed as a potential transdiagnostic mechanism underlying emotional disorders, underscoring the need for reliable assessment. This study conducted a multi-stage development and validation of the Engaging in Life Scale (ELS). Participants were 2,420 Chinese adults aged 18–65 recruited from the prescreening phase of a randomized controlled trial on emotional distress, ensuring inclusion of individuals with varying symptom levels. An initial item pool was generated through qualitative interviews and expert review, then refined via item analysis and exploratory factor analysis, yielding a 17-item scale (ELS-17) encompassing four dimensions—work/study, socializing, leisure, and sleep routine. Confirmatory factor analysis in an independent subsample supported this four-factor structure, with high reliability (α = 0.83–0.91) and satisfactory construct validity (CR = 0.87–0.93; AVE = 0.64–0.78). Multidimensional item response theory indicated strong measurement precision and measurement invariance across gender. To enhance applicability, a short form (ELS-8) was derived using the ant colony optimization (ACO) algorithm, retaining two items per dimension while preserving model fit, reliability, and criterion validity. The ELS-8 showed excellent fit and very high correspondence with the ELS-17 (r = 0.98). Overall, the ELS provides a theoretically grounded and psychometrically sound measure of engaging in life in both long and short forms, offering a solid foundation for future cross-diagnostic and clinical research.