Teacher preparation programs include a variety of field experiences designed to support preservice teacher growth including early field experiences, student teaching, and clinical internships. Limited research was available regarding how hosting a preservice teacher may result in long-term learning and professional growth (Bruemmer, 2018; Gallo-Fox & Scantlebury, 2015; Marciano et al., 2019; Pylman, 2016). It was also unknown to what degree mentor teacher professional growth was impacted by the placement type or related to years of experience. The primary purpose of this study was to empirically evaluate whether mentor teachers reported experiencing significant professional growth and whether perceptions of professional growth are impacted by placement type or related to years of experience teaching or years of experience in mentoring. A comparative, quantitative methodology and survey research design was adopted to investigate this problem. Quantitative data was collected electronically using the Mentor Teacher Survey (Appendix A). Survey participants included mentor teachers from Southeast and South Central Pennsylvania who have hosted a preservice teacher within the past five years. Statistical tests included one-sample t-tests for each of the three categories of professional growth to determine if significant professional growth was reported, the One-Way MANOVA statistical test to compare mentor teachers' perceptions of professional growth across groups, and the Spearman's Rho correlation to examine the relationship between perceived professional growth and years of experience. The results of the statistical analyses showed that mentor teachers did not report receiving significant professional growth in instructional practices, mentoring and leadership skills, or instructional leadership self-efficacy as a result of hosting a preservice teacher from an early field experience, student teaching placement, or internship. The findings did demonstrate that mentor teachers who hosted interns reported significantly more professional growth in instructional practices and instructional leadership self-efficacy than mentor teachers who hosted preservice teachers from early field experiences. No statistically significant relationships were discovered between professional growth and years of experience teaching or years of experience in mentoring. [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.]