Effective teacher training programs entail cultivating not only professional teaching competencies but also promoting psychological strengths. However, there is a lack of investigation into how different modes of delivering psychological interventions influence well-being outcomes in the teaching profession, such as preschool educators. This study examines the effects of different technologically driven modes of implementing a PROSPER-based psychological intervention on positivity, relationship, outcome, strengths, purpose, engagement, and resilience. One hundred twenty-eight pre-service preschool teachers were randomly assigned to (1) the full intervention (i.e., online workshop and smartphone app); (2) the online workshop; (3) the smartphone app; and (4) the wait-list control group. The results demonstrated that the online workshop mode yielded the strongest intervention effects on well-being outcomes: positivity, purpose, engagement, and resilience. Although the smartphone app mode did not significantly improve psychological outcomes, combining this approach with the online workshop format appeared to have positive retention effects on positivity at the Time 3 follow-up. The findings suggest that the traditional mode of implementing positive psychological interventions could be more effective than the smartphone app-based mode in bolstering pre-service teachers' well-being. Copyright © 2023 International Association of Applied Psychology.