Spaced education (SE) is a learning strategy that can improve long-term knowledge retention. Inspired by the concept of SE, we conducted a mixed methods study of a smartphone application (app) as a platform of SE. Objectives were to: (phase 1 quantitative) estimate the extent to which weekly alerts on the app can stimulate medical residents to visit the app, (connection of phases) identify participants for a second qualitative phase, and (phase 2 qualitative) describe factors, from the resident perspective, which influence sustainable participation in SE, and describe strategies for improvement of the app. Methodology and methods: phase-1 design was pre-experimental, phase-2 design was qualitative descriptive (deductive-inductive thematic analysis). Results: We observed a stimulating effect of weekly alerts for the first two months of the one-year study. Per participant, alert visits varied from 0 to 34 (mean = 1.7, SD = 4.5) and total page visits varied from 1 to 442 (mean = 28.3, SD = 61.4). Barriers and facilitators to sustainable participation in SE fell into five dimensions: user-related factors, information content factors, mobile app design factors, alert system factors, and service factors. Four strategies for app improvement were described. In conclusion, we propose five dimensions pertaining to potential predictors of sustainable participation in SE to deliver clinical information.