The study described in this book was designed to gain knowledge about the relationship between teacher level measures, calculated from student standardized test scores, and actual teacher performance. The study used a quantitative method and correlational design to study central Florida secondary schoolteachers. The study sought to avoid the subjective bias observed in previous studies by comparing two different objective measures of student achievement (value-added measures and level measures). The results, based on 15 teachers and 359 student test scores collected over a three-year period, suggest that value-added measures are strongly correlated with level measures (mean test scores). Additionally, the study data suggested that the strength of this correlation decreases from eight through tenth grade. In conclusion, the study found that value-added indicators measure nearly the same factor as level indicators. Considering the complication and expense of calculating value-added measures, level measures may be more attractive in light this study.