The purpose of this study was to examine student achievement as a function of principal personality and assistant principal personality in an elementary school setting. Student achievement, the dependent variable, was fifth grade campus mean scale scores on the Texas Assessment of Academic Skills test for reading, math, and science. Holland's (1973) theory of person-environment fit was adapted to test the relationship of principal and assistant principal consistency, differentiation, and congruence to student achievement. This study included 23 elementary schools in one school district in the central Texas area. Principals and assistant principals were administered the Self-Directed Search to obtain three dominant personality traits. Consistency, differentiation, and congruence scores were calculated for the principals and assistant principals. A partial correlation controlling for percentage of low socioeconomic status and limited English proficiency revealed principal consistency was inversely related to student achievement which was counter to theoretical predictions. Principal differentiation and assistant principal consistency were positively associated with student achievement. These findings partially supported Holland's theory of person-environment fit while raising questions about certain theoretical predictions. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]