Long-term monitoring is integral to assessing ecological trends, but fluctuations in funding, available resources, and institutional priorities present challenges to the sustainability of monitoring programs. Incorporating community science has the potential to increase the spatial and temporal extent of monitoring efforts while minimizing cost and may be particularly useful for monitoring under-funded species such as amphibians. Concern over the reliability and integrity of data collected by volunteers, however, hampers broader use of community science in ecological monitoring. We assessed the quality of data collected by and the reliability of community scientists participating in a collaborative amphibian monitoring project requiring strict adherence to data collection protocols. Community scientists’ ability to correctly identify and detect species was on par with that of professional biologists. Agreement in species detected by community scientists and biologists ranged from 77% to 99% at sites surveyed by both surveyor types in the same season and modeled detection probabilities were similar for all but one species. Follow-through within a season was high. Since 2014, community scientists (n = 328) completed 75% of surveys to which they had committed. However, retention of community scientists across years was low, with 81% of participants only involved for one season. Community scientists offset agency resource limitations by conducting 32% of surveys and substantially contributed to meeting sample size goals. Furthermore, although time invested in project management and coordination increased with community science involvement, cost savings from field surveys and centralized coordination offset this increase. Our results suggest that with careful project planning and volunteer training, community scientists can contribute robust data to rigorous scientific studies, but project and participants’ goals must align to improve retention across years. Successful programs will require substantial investment by personnel for volunteer recruitment, training, data validation, and dissemination of results, however, involvement of community scientists can improve the sustainability of long-term monitoring programs through collaboration and cost savings. Our results support an increasing body of evidence that community science can contribute significantly to ecological monitoring even when considerable commitment and scientific rigor are essential.