The federal government operates under certain laws, rules, and policies that differ in significant ways from those that apply to any other institution. Federal agencies must comply with constitutional principles, statutory obligations, regulatory processes, and administrative policies. When new federal activities like crowdsourcing meet rapidly changing technologies, initially unrecognized legal issues may arise that lack precedent and therefore require agency lawyers to scramble to keep up with developments. The purpose of this report is to review legal and regulatory issues that federal agencies face when they engage in citizen science and crowdsourcing activities. The report identifies relevant issues that most federal agencies must consider, reviews the legal standards, suggests ways that agencies can comply with or lawfully evade requirements, and discusses practical approaches that can ease the path for federal citizen science and crowdsourcing projects, including procedural activities, cooperative actions, legislative changes, and regulatory adjustments.