The USA National Phenology Network (USA-NPN) is the premier source of information regarding plant and animal phenology, the timing of life-cycle events such as leaf budburst, flowering, and fruiting or insect adult emergence, in the United States. Phenology observations maintained by USA-NPN are contributed by professional and volunteer observers at tens of thousands of locations across the country, and these data are used widely in science, science communication, and management. However, critical limitations in the USA-NPN’s data collection and access infrastructure currently limit public engagement and research use from reaching their fullest potential. This work will result in major improvements to the USA-NPN’s data collection mobile app and to data access tools. These enhancements are expected to lead to substantial growth in volunteer participation, especially from locations and communities of people that do not yet participate. Engaging a larger and more diverse community in data collection will result in a more robust, balanced, and representative phenology dataset, which will contribute to societal well-being through the provision of better ecological data to inform decision-making. The full set of activities directly links to our ability to understand planetary resilience.<br/><br/>The USA National Phenology Network is a national-scale program focused on the collection, provisioning and use of plant and animal phenology data. In this study, the researchers will make major improvements to the USA-NPN’s technical infrastructure in order to lower barriers to entry for new and continuing public participants who collect phenology data and increase engagement and connections among participants. In particular, we will develop observing challenges, in-app badges, enhanced, tailored user notifications and multilingual support for the USA-NPN mobile app. This work will also support science and management use by ensuring data quality through the addition of photo storage, computer-aided identifications, and enhanced discoverability. In particular, the researchers will improve tools to access data, and periodically publish the dataset to the Global Biodiversity Information Facility. These participation and user-focused improvements will lead to a redesigned, easier-to-use set of access points for the research community, and integration into global ecological data-sharing initiatives with a focus on FAIR (Findable, Accessible, Interoperable, Reusable) data. Finally, this work will support training and new opportunities for graduate and undergraduate students interested in the public participation in science.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.