This research investigated the relationship of math intervention teachers' (MITs) pedagogical content knowledge (PCK) and students' math achievement gains in primary math interventions. The Kentucky Center for Mathematics gathered data on the MITs and primary math intervention students included in this study. Longitudinal data were analyzed for a sample of 65 teachers with one to four years of experience as math interventionists. Analyzed student data were from an 889 student sample (kindergarten to grade three) from the fourth year of Kentucky's math interventions. The students in the sample were taught by the teachers in the sample, using Mathematics Recovery, Add+Vantage Math Recovery, and Number Worlds math intervention programs. The study examined how achievement gains were affected by teachers' years of math intervention experience; hours of training, collegial support, and contact with students for instruction; and scores on the Learning Mathematics for Teaching test as a measure of pedagogical content knowledge. The investigation also considered the impact of students' grade, gender, history of retention, prior math achievement, and whether they received services through special education. The dependent variable in all analyses was student math achievement score gains: the difference in students' scaled scores on pre and post-intervention administrations of Terra Nova Math achievement tests. A significant positive correlation was identified between students' math achievement gains with their contact hours with the MIT for math instruction (r = 0.23, p < 0.00). PCK had significant positive correlations with teachers' hours of training and years of MIT experience (r = 0.07, p < 0.00 and r = 0.12, p < 0.00, respectively). Regression analysis identified contact hours for instruction, lower grade level, teachers' PCK, and students' IEP status as significant predictors of math achievement gains. Students with more contact hours and students in lower grades made greater math achievement gains. Teachers' PCK had as much influence on student achievement as disability status. Analysis of Covariance and post hoc analyses determined that when entry math achievement scores were used to rank intervention students in quartiles, students in the lower quartiles made greater gains compared to peers in higher performing quartiles. [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/en-US/products/dissertations/individuals.shtml.]