Emotion differentiation (ED) – complexity in the mental representation and description of one’s emotional experiences – is important for mental health. However, less is known whether ED can be enhanced in adults. We investigated if scaffolding emotion language use during affect labelling – initial provision of emotion word prompts (close-ended) followed by free response (open-ended) – impacts ED and psychological health. Utilising a crossover design, 92 college students completed questionnaires assessing psychological health at three time-points and ecological momentary assessment of emotions, affect valence and emotional self-efficacy for 14 days. Participants were randomised to the “scaffolding” group, where they reported emotions using the close-ended (7 days) followed by open-ended (7 days) approach, or the reverse sequence (control group). We extracted two ED indices: traditional intraclass correlation coefficient from close-ended reports and novel specificity index from open-ended reports. Primary analyses examined group differences across weeks while exploratory analyses examined moment-to-moment differences using multilevel modelling. Relative to controls, the scaffolding group demonstrated greater ED during open-ended emotion reporting of negative emotions and associated shifts in negative affect and emotional self-efficacy. There were no significant group differences in psychological symptoms. Results provide preliminary evidence that scaffolding may enhance ED and have implications for psychological intervention.