Personality types and practices are presumed to play a significant role in the improvement of schools' performance. This paper presents the findings from the analysis of quantitative data drawn from a larger study that examined the relationship between headteachers' personality types, instructional supervision practices, and performance. The study adopted a descriptive survey research design to collect data by utilizing a self-developed and Self-Directed Search (SDS) questionnaire that participants answered. A census sampling was conducted with 71 and 37 headteachers from Embu East and West public primary schools, respectively giving 108 participants. The data collected was analyzed using SPSS for descriptive and inferential statistics. Spearman's rank correlation coefficient was used to determine any relationship between personality types, instructional supervision practices, and schools' performance. The findings of the study revealed a significant statistical relationship between enterprising personality types and schools' academic performance (r =0.125*, p<0.05). Further, the results revealed that there is a positive (r=0.229, P<0.05) relationship between realistic personality type and holding parents-pupils-teachers' conferences while among conventional types, there is a negative (r=-0.223, p<0.05) correlation in giving teachers feedback. The significance of this study is that headteachers' personality types do not influence instructional supervision practices, which is a unique finding indicating that other factors influence instructional supervision practices.