This study responds to a request from the National Board for Professional Teaching Standards to analyze National Board certification among high school teachers in understudied subject areas and locales to help fill gaps in the research literature. The authors also were asked to use multiple indicators of performance. The research team selected two new locales for this analysis, the Commonwealth of Kentucky and the Chicago public schools. Chicago, a racially and ethnically diverse city with a population of more than 2.8 million, has one of the largest urban school districts in the country. Kentucky, by contrast, is a largely rural state with some suburban and urban areas. Together, these two locales encompass a full range of public school settings. In addition to examining student test scores, the authors also conducted classroom observations of the instructional practices of high school teachers in science and mathematics, comparing a sample of National Board Certification (NBC) applicants and similar teachers not pursuing this certification. Using the data gathered, the authors found evidence that National Board certification is an effective signal of teacher quality, based on student test scores. They also found evidence that the certification process successfully screens applicants based on their effectiveness. They were unable, however, to find evidence that the certification process itself enhances the instructional quality or effectiveness of teachers who choose to go through it. The following are appended: (1) Leadership by Design (Science Classroom Observation Instrument and Mathematics Classroom Observation Instrument); (2) Rubric for Scoring Classroom Observations (Science Rubric and Mathematics Rubric); (3) A Pilot Test of the Leadership by Design Scoring Rubric for Assessment of Instructional Quality; (4) Construction of the Student Analytic File; (5) Complete Results from All Model Specifications and Outcomes; and (6) Analysis of Ceiling Effects on Instructional Improvement. A glossary, a list of figures, and a list of tables are also included. [This report was written with Christine Mokher, Thomas Geraghty, and Lauren Sartain.]