School Resource Officers (SROs) are a growing profession in public schools across the country. With the increase of school shootings, the number of SROs has proliferated without federal or state standards or evaluations. This mixed methods study examines the perceptions of 135 teachers in 6 different regions of Missouri. Through surveys and 15 interviews, the perceptions teachers hold about the full-time SROs in the building are aligned with SRO Triad: educator, informal counselor, and law enforcement officer. Themes are compared to quantitative findings to provide triangulation and credible evidence. The characteristics of law enforcement officer were the most agreed upon by teachers. Great variation was seen in the behaviors reported in the realm of informal counselor, while the role of educator was found to be less agreed upon among teachers. Discussion of these findings include the extension of research from other stakeholder groups and the implications of the need for further research in this area. Recommendations for practice are presented including the use of a Memorandum of Understanding (MOU), standardizing SRO roles and responsibilities, and involving teachers in defining this role in the building. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]