The purpose of this quantitative correlational study was to determine to what extent principal instructional leadership practice (PIL) and collective teacher efficacy (CTE) combined or individually significantly predict teacher affective (ACS), continuance (CCS), and normative commitment (NCS) in Maryland school districts. This study was based on Bandura's social cognitive theory, organizational commitment theory, and the framework of principal instructional leadership. This study utilized an anonymous survey with a convenience sample of 159 public middle school teachers in grades 6-8 at Prince George's County Public School, Maryland. The survey consisted of three instruments: the PIMRS, the CTE, and the subscale of the teacher commitment scale (ACS, CCS, and NCS). The research questions addressed to what extent PIL and CTE combined/individually significantly predicted teacher affective, continuance, and normative commitment in a school district in Maryland. Three multiple regression analyses were used to answer three research questions. The results suggested that PIL and CTE significantly predicted teacher affective and normative commitment. However, PIL and CTE did not significantly predict teacher continuance commitment. The overall regression analysis of PIL and CTE prediction on teacher affective commitment was statistically significant at F(2, 156) = 23.419, p < 0.001, R[superscript 2] = 0.231, continuance commitment was statistically insignificant at F(2, 156) = 0.723, p =0.487, R[superscript 2] = 0.009, and normative commitment was statistically significant at F(2, 156) = 13.875, < 0.001, R[superscript 2] = 0.151. [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.]