The purpose of this quantitative quasi-experimental study was to analyze the effect of one type of professional development, Japanese lesson study, on student achievement at the high school level. The study examined the effect by comparing student achievement of students with non-lesson study teachers (control group) and those using the lesson study (experimental group) technique. This post-test only study examined the end of instruction (EOI) achievement scores of students taught by teachers receiving lesson study (LS) training and students taught by teachers not receiving LS training. The source for these findings was Algebra I EOI and Biology I EOI assessments mandated by the state to meet "No Child Left Behind" (NCLB) requirements. Through the analysis of data from the Algebra I and Biology I EOI exams, determining the mean score of the students in the experimental group and the control group and conducting t tests, statistically significant differences were suggested by the data indicating LS training did have a positive influence on student achievement. The data analyses were consistent with the germinal and current literature that utilized limited qualitative data. The data assist in filling the gap regarding quantitative data and the effect of Japanese lesson study on student achievement. [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.]