For population-wide impact of interventions, evidence-based programs must be successfully disseminated and adopted at scale. Research-practice partnerships can legitimize programs and support organizational adoption, however, ways of leveraging the contributions of partners during dissemination processes are less clear. TransformUs is a school-based physical activity and sedentary behaviour program, and since 2018, has been disseminated at scale to all primary schools in Victoria, Australia, in partnership with 16 state and national organizations. The study objective was to investigate the experiences of partner organizations disseminating TransformUs within their networks, and factors associated with awareness and adoption of the program in schools, from the perspective of partner organizations. Semi-structured interviews with representatives from 15 (out of 16) partner organizations in 2019 involved in disseminating TransformUs state-wide. An interview guide was informed by the RE-AIM framework. Interviews were audio-recorded, transcribed, and coded anonymously. Data were analysed thematically. Four themes (and 13 sub-themes) were identified: (i) organizational barriers and facilitators to dissemination; (ii) implementation support for partners; (iii) overall research experience; and (iv) dissemination strategy. Partners used multiple dissemination channels to increase adoption, and strong alignment between TransformUs and the partner organization's goals appeared to enable dissemination. Partners outlined several local, regional, and state organizations to partner with, and offered suggestions regarding preferred content and timing of dissemination activities for their networks. Researchers planning research-practice partnerships should proactively consider organizational barriers partners may face during dissemination. Regular communication and feedback on dissemination outcomes may contribute to positive research-practice experiences and allow for tailored dissemination strategies.