Although self-regulated learning has been identified as important for students in academic settings, the construct of teacher self-regulation is less well understood. The literature on teacher self-regulation is reviewed in this dissertation, identifying the weaknesses of studies to date and gaps in the literature. The largest gap is the existence of a valid measure of teacher self-regulation that can be used in the U.S. K-12 teacher population. Without such a measure, the possible relationships between teacher self-regulation and important outcomes like teacher learning, student self-regulation, and student achievement cannot be examined. By collecting evidence from various sources (i.e., expert review, teacher review, teacher responses, factor structure, etc.), this dissertation evaluated the reliability and validity of the English-version of the Teacher Self-regulation Scale (TSRS), which was originally developed and validated in Turkey and has since been validated in the Iranian English-as-Foreign-Language (EFL) teacher population. The TSRS, consisting of 40 items, is based on a theoretical model of self-regulation proposed by Zimmerman (2000) and captures nine factors. A series of confirmatory factor analyses (CFA) were conducted to test the factor structure using responses collected via an anonymous online survey from 923 U.S. K-12 teachers recruited from teacher professional organizations. In addition, the internal consistency of the nine subscales were assessed. In this sample, the nine-factor model did not fit the data well suggesting possible cross-cultural differences. Furthermore, unidimensionality was confirmed for only eight of the nine subscales: emotional control, goal setting, help seeking, intrinsic interest, mastery goal orientation, performance goal orientation, self-evaluation, and self-instruction. Theoretical relationships between teacher self-regulation subscales and another measure of teacher self-regulation, teacher sense of responsibility and teacher self-efficacy were also tested using a series of path analyses. A series of multiple regression analyses identified a number of demographic variables as significant predictors of teacher self-regulation subscales. Across the eight subscales, being a teacher of English/Language Arts and a female were significant predictors of higher TSRS responses, whereas being a native English speaker significantly predicted lower TSRS responses. There was also a significant positive relationship between years of teaching experience and TSRS responses for a number of subscales. Further research is needed to better represent the construct of teacher self-regulation.