This study investigates beneficial effects on emotional regulation and wellbeing of young adults from using an app designed to promote cognitive reappraisal. Seventy-eight first-year college students (aged 18–19) participated in the study: 36 (71% female) were assigned to the experimental group and used the app during 2 weeks; 42 students (73% female) were assigned to the control group and used an app prompting generic expressive writing during the same period. Self-reports assessed participant perceived stress, anxiety, and wellbeing pre and post, and physiological arousal (SCL) was assessed during the post- assessment. Participants’ answers to the app tasks were also analyzed linguistically. ANOVAs showed that using the cognitive reappraisal app was associated with lower levels of anxiety, perceived stress, and physiological arousal, and with greater wellbeing. In the linguistic tasks of the apps participants in the experimental group used more words linked to analytic thinking and cognitive processes, and showed to be more focused on the future. These results provide preliminary support for the potential of mobile technologies to promote emotional regulation and resilience among young adults.