Federal initiatives and other research have led states across the nation to sharpen their focus on teacher evaluation in recent years. In 2009 a seminal report, "The Widget Effect," from The New Teacher Project revealed that in districts using a binary rating system to evaluate teachers, less than 1 percent of teachers received an unsatisfactory rating. The remaining 99 percent were, in effect, like widgets, undifferentiated as individual professionals. Since then, a growing body of research on teacher evaluation systems has indicated that classroom observation ratings often cluster around the middle or high end of evaluation scales. The research has also found that observation ratings are susceptible to several biases, such as incoming student achievement and school, classroom, and rater characteristics. Thus many education decision-makers lack sufficient information to make personnel decisions and to effectively support teacher growth and development. Texas is among the states that have identified teacher evaluation and support as a high priority for education policy. In 2014/15 the Texas Education Agency piloted the Texas Teacher Evaluation and Support System (T-TESS) in 57 school districts. The pilot was followed by a refinement phase in 2015/16 and statewide rollout in 2016/17. During the pilot year teacher overall ratings were based solely on rubric ratings on 16 dimensions across four domains (planning, instruction, learning environment, and professional practices and responsibilities), although T-TESS also includes a student growth measure that was piloted simultaneously. The study examined the statistical properties of the T-TESS rubric from the 2014/15 pilot year to explore the extent to which it differentiates teachers on teaching quality and to investigate its internal consistency and efficiency. The study also explored the relationships between rubric ratings and school characteristics to investigate whether certain types of schools have teachers with higher or lower ratings. The study's findings have several implications for practice and research. The findings suggest that the T-TESS rubric demonstrates potential to be an effective, consistent, and efficient evaluation rubric. Thus, the Texas Education Association and local education agencies have a promising tool for providing evidence-based feedback and targeted professional development. Future research could try to validate ratings based on the T-TESS rubric against other measures of teacher effectiveness (for example, student growth). Such validation could shed light on whether a relationship exists between rubric ratings and a teacher's contribution to student achievement. Moreover, future studies could explore whether relationships exist between the T-TESS rubric and classroom and district characteristics. Such analysis may unearth the extent to which effective teachers are equally distributed within schools and within and across districts. Finally, further research could explore whether implementing teacher evaluation systems translates into improvements in teacher effectiveness or in long-term outcomes, such as teacher retention and student achievement.