Introduction: The struggle of many small rural and remote communities to sustain comprehensive primary healthcare (PHC) services is an issue of global interest. Recent research has identified essential service requirements (workforce, funding, management, linkages, and infrastructure) and environmental enablers (supportive policies, Commonwealth and state/territory relations, community readiness) associated with the provision of high-quality PHC services in these communities. However, little is known about how best to expand the provision of core high-quality PHC services to the many small and diverse non-metropolitan communities that currently lack them. This study investigates the transition of an integrated model of PHC service delivery, which provided PHC services to a single community, to a rurally ‘networked’ model of PHC delivering PHC to multiple communities. It seeks to enhance understanding of the factors and processes enabling and impeding successful PHC service expansion into small rural communities. Salient lessons for other rural health services seeking to expand into neighbouring small rural communities are proffered. Methods: This mixed-methods study of the expansion of Elmore Primary Health Service in northern Victoria, Australia, into eight neighbouring rural communities was conducted using audio-recorded semi-structured interviews with members of staff (n=11). Staff members were purposively sampled according to their knowledge and experience of the expansion, ensuring that a broad range of perspectives were captured and that these related to each of the eight sites. Additionally, interviewees completed a questionnaire indicating the importance of 16 different factors to the service expansion. Results: Community engagement, vision and leadership, linkages with other health services, improving residents’ access to PHC, broadening the range of care provided and professional satisfaction were each identified by almost all participants (>90%) as having very important associations with successful expansion. A conceptual model with five distinctive stages was developed to explain the processes underpinning PHC service expansion: initiative, consultation, roll-out, evaluation and consolidation. Previously identified essential service requirements and key environmental enablers come in to play at different stages of expansion. Working closely with communities and community stakeholders, however, is critically important at all stages of expansion. The expansion of the Elmore Primary Health Service to a regionally ‘networked’ PHC model conferred substantial benefits by virtue of the assistance that could be provided to individual services to effectively manage change and meet essential service requirements in rapidly changing circumstances. Conclusions: This evaluation of a ‘networked’ model of PHC in rural areas identified the factors and processes underpinning service expansion during five distinct stages, represented in a conceptual model of service expansion. The full range of key environmental enablers and essential service requirements were very important for successful expansion, particularly during roll-out and consolidation stages, whilst community engagement was important at all stages.