BackgroundGrowing evidence substantiates the unique contribution made by fathers to adolescent mental health and the potential for them to benefit from preventive parenting programs. Nevertheless, male parents are markedly under-represented amongst users of these programs. This extends to programs delivered online, despite the increased flexibility and accessibility of web-based platforms which may better suit the needs of fathers. Therefore, this study aimed to explore perspectives of fathers on the lack of father engagement with web-based preventive parenting programs for adolescent mental health. MethodWe conducted semi-structured interviews with fifteen Australian fathers of an adolescent aged 12-18 years, who had never used a web-based parenting program for adolescent mental health. An iterative thematic qualitative approach was used. Participants were aged between 42 and 57 years (M = 49.0, SD = 4.3) and living in Melbourne, Australia. ResultsThematic analysis identified four broad themes which may deter their use of web-based parenting programs: 1) limited awareness of these programs, 2) perceptions that limit motivation to use them, 3) uncertainty about their role in parenting for adolescent mental health, and 4) design aspects of programs. ConclusionOur findings indicated that strategies which address practical barriers to accessing programs alone are unlikely to enhance fathers’ engagement. Findings from this study provide feasible avenues for developing and implementing father-inclusive web-based parenting programs. Adopting these solutions can potentially address parenting factors amongst fathers with a view to improving adolescent mental health outcomes.