The University of California-Davis and its collaborators are identifying and testing strategies for implementing a model citizen science program that links the statewide Master Naturalist program with local citizen science projects that engage the public in environmental scientific research. The goals of the project are to develop a mechanism for broadening the reach of master naturalist and citizen science programs, and measure the impact of these programs on participants' science learning and environmental stewardship behavior. The project is (1) implementing strategies for engaging underserved audiences (young adults and communities of color) and enhancing learning for seniors in the California Naturalist program, (2) developing and testing a citizen science training module, (3) establishing two regional volunteer naturalist networks in Northern California that have links to local citizen science projects, and (4) developing web tools for use by program providers and naturalists to connect to projects and promote science learning. Project deliverables include training sessions, support services, network coordination, web tools, research on impacts on science learning, and participant tracking. By bringing together young and older adults to learn together, merging these audiences will result in the formation of a diverse corps of citizen naturalists who participate in ecological monitoring of local natural areas and conduct land stewardship activities. The project's findings will help program administrators scale-up the approach statewide and across the nation.