Libraries are local community centers and hubs for learning, with increasing numbers of public libraries responding to the need to increase science literacy and support 21st century skills by adding STEM programs and resources for patrons of all ages. The Institute for Global Environmental Strategies (IGES), through the NASA Earth Science Education Collaborative (NESEC) cooperative agreement, is working with several libraries to pilot and implement collaborative models for engaging their local communities in STEM and citizen science. During spring and summer 2019, eight public library systems across the United States piloted activities and programs related to NASA’s GLOBE Observer citizen science app, which enables citizen scientists to contribute observations that complement NASA Earth observations. These include activities related to citizen scientist observations of Clouds (photographing clouds and recording sky observations), Mosquito Habitat Mapper (identifying water sources that are potential mosquito habitat and the presence of mosquito larvae; sampling and counting larvae; and using a clip on magnifier to identify the type of mosquito), and Land Cover (photographing the landscape and classifying land cover). Examples include the Pioneer Library System in Oklahoma, Southwest Oklahoma City Public Library, that is implementing GO Oklahoma! a citizen science campaign to collect GLOBE Observer Mosquito Habitat Mapper observations to support research by partner scientists at University of Oklahoma-Norman and Southern Nazarene University. The Los Angeles Public Library System has been field testing GLOBE Observer activities as part of its Neighborhood Science Program and will be incorporating these resources into circulating kits the library is developing for citizen scientists related to GLOBE Clouds and Mosquito Habitat Mapper that they will be piloting with Los Angelenos during fall 2019. Insights from the library pilot testing and programs include promising practices, requested resources, programming ideas and approaches, and particularly approaches to leveraging NASA subject matter experts and networks, to support local library programming.