The most efficacious psychosocial intervention for reducing attention-deficit/hyperactivity disorder (ADHD) symptoms in young children is behavioral parent training (BPT). Potential benefits are hindered by limited accessibility, low session attendance, and poor implementation of prescribed strategies. As a result, only approximately half of families with young children with ADHD receive BPT. We describe an innovative approach for reducing barriers to BPT access. Specifically, we invoked an iterative, 5-step process of intervention development and revision to modify an existing face-to-face BPT program and develop an online version. Results indicated that the revised program and online versions (a) increased parent engagement with BPT, (b) enhanced accessibility, (c) produced favorable parent acceptability and feasibility ratings, and (d) resulted in improved child outcomes.