Citizen Science is emerging as an innovative strategy to engage K-12 students in authentic science practices and relevant, real world phenomena. Citizen science is traditionally an informal science experience, with members of the public choosing to participate in the scientific research process through contributing data or other related efforts. In the school setting, the teacher is the primary mediating factor in whether students will participate in citizen science. Teacher perceptions and beliefs play a significant role in teachers' decision-making about how curriculum is implemented in the classroom. In the Fall of 2020, first grade teachers from a large public school district were offered a science unit of study that included a citizen science lesson. Using a mixed method approach, data from 75 surveys and 12 interviews were used to elucidate patterns and relationships between teachers' beliefs about science teaching and learning, their decision making, and participation in citizen science. Four themes emerged: (1) teachers need awareness, time, training, and support in order to implement a new or novel curriculum such as Citizen Science, (2) teachers believe that the location and/or environment in which students do science, especially citizen science, requires the presence of the teacher, (3) teachers believe in equity, specifically that all students should be able to participate in citizen science and have equitable access to resources, and (4) teacher beliefs about teaching and learning science align with their perceptions of potential learning outcomes from participation in citizen science. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]