The purpose of this study was to examine one urban elementary school to determine the influence of PLCs on administrator and teacher efficacy in supporting academic success. Using Stewart, Williams, and Matthew's (2009) Learning Community Culture Indicator (LCCI), which is based on the work of Richard DuFour (2006) and Eaker and DuFour (1998), the researcher identified and measured five characteristics of professional learning communities among 81 teachers and 18 administrators. Additionally, examining Bandura's core construct of efficacy (1997, 1988) provided a method for understanding the roles of the teacher and administrator within the professional learning community. Conducting ANOVA tests and 14 interviews with 7 administrators and 7 teachers, the researcher used a mixed method design to gain additional insight otherwise not available from the survey alone. The study results indicated a statistically consistent relationship between administrator and teacher efficacy and professional learning communities. The results indicated that an emphasis on professional learning communities in one urban elementary school in Northern New Jersey has the potential to support academic success. This study also enabled the researcher to identify specific themes pertinent to administrator and teacher efficacy. [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.]