Abstract: Mobile technology presents an exciting opportunity for social workers to reach populations that are typically underserved by interventions and services. We present one application of technology that is particularly relevant to social work practice. The mDad (Mobile Device Assisted Dad) smartphone application (app) was developed to augment existing social work practices by providing a father-friendly tool to help new fathers learn about and engage with their infants and toddlers. We discuss the process of developing the smartphone app content and conducting usability testing of the mDad app. We conclude with a discussion of the lessons learned from the mDad project and the challenges of implementation contexts.