In recent years, citizen science projects have emerged as a means to involve students in scientific inquiry, particularly in the fields of ecology and environmental science. A citizen scientist is "a volunteer who collects and/or processes data as part of a scientific inquiry" (Silverton 2009, p. 467). Participation in citizen science fosters an appreciation for the diversity of scientific fields (i.e., conservation biology, ornithology). The National Science Foundation (NSF) supports citizen science projects as a means to recruit future generations into the science, technology, engineering, and mathematics (STEM) disciplines by directly involving students in scientific research. Teachers have expanded citizen science projects to include not only gathering and analyzing data but also civic participation and action (Zaikowski and Lichtman 2007; Ryken et al. 2008). This effectively merges hard sciences with social sciences. In this article, the authors present the multidisciplinary Project Citizen approach to teaching and learning science and engaging students in action-oriented citizen science. Project Citizen, a curricular program administered by a national network of coordinators in every state, promotes competent and responsible civic participation by giving students a vehicle to influence and monitor public policy (Center for Civic Education 2009). High school teachers can adapt Project Citizen as an approach for teaching a variety of subject areas. English teachers can use Project Citizen to emphasize speech and writing skills; social studies teachers can emphasize civic ideas and practices; and mathematics and science teachers can focus on analytical thinking and scientific inquiry. (Contains 3 figures and 2 online resources.)