Community-based approaches to natural resource management are being discussed and experienced as promising ways for pursuing ecological conservation and socio-economic development simultaneously. However, the multiplicity of levels, scales, objectives and actors that are involved in sustainability transformations tends to be challenging for such bottom-up approaches. Collaborative and polycentric governance schemes are proposed for dealing with those challenges. What has not been fully explored is how knowledge from local contexts of community-based initiatives can be diffused to influence practices on higher levels and/or in other local contexts. This study explores how theoretical advances in the diffusion of grassroots innovation can contribute to understanding and supporting the diffusion of knowledge and practices from community-based initiatives and proposes a transdisciplinary approach to diffusion. For that aim, we develop an analytical perspective on the diffusion of grassroots innovations that takes into consideration the multiplicity of actors, levels and scales, the different qualities/types of knowledge and practices, as well as their respective contributions. We focus on the multiplicity and situatedness of cognitive frames and conceptualize the diffusion of grassroots innovations as a transdisciplinary process. In this way three different diffusion pathways are derived in which the knowledge and practices of grassroots initiatives can be processed in order to promote their (re)interpretation and (re)application in situations and by actors that do not share the cognitive frame and the local context of the originating grassroots initiative. The application of the developed approach is illustrated through transdisciplinary research for the diffusion of sustainable family farming innovations in Colombia. This conceptualization accounts for the emergence of multiplicity as an outcome of diffusion by emphasizing difference as a core resource in building sustainable futures.