Otieno, MichaelMagoma, Charles M.2022-02-102022-02-102022-02European Journal of Education Studies - Volume 9 │ Issue 2 │ 20222501-1111http://dx.doi.org/10.46827/ejes.v9i2.4155http://ir-library.ku.ac.ke/handle/123456789/23149A research paper in European Journal of Education Studies - Volume 9 │ Issue 2 │ 2022With the core business of the school being instruction, the principals’ monitoring of instructional assessment is necessary in enhancing teaching and learning processes and outcome in schools. Despite measures being in place, teaching and learning outcome has remained consistently low, especially in Kajiado County. The objective of this study is to assess the influence of principals’ monitoring of instructional assessments on teaching and learning outcome. The study was guided by the result-based management theory. The study employed a descriptive survey design. This study population of study comprised 727 respondents in all the 9 public secondary schools in Kajiado. These respondents included 122 teachers, 594 students and 9 principals. Out of these, 342 respondents were sampled and they were comprised of 9 principals, 97 teachers and 201 students. Proportionate sampling was used to draw a sample of 97 teachers’ and 201 students per school. Further, simple random sampling was used to sample teachers while convenience sampling was applied to draw the sample of students to participate in the study per school. Data was collected by questionnaires and interview schedule. A pilot study was conducted in two schools for the purpose of addressing validity and reliability of the instruments before the actual study was conducted. Content validity was determined by seeking the judgment of professional experts in the area of educational research, evaluation and assessment. Reliability level was ascertained by using Cronbach’s alpha technique to check internal consistency of the instruments. The analysis of quantitative data was done using frequencies, percentages and means and then presented in tables and figures. Qualitative data was arranged into themes and presented through narration and in verbatim. The study established that principals' checking of assessment practices, even-though inconsistent, significantly influenced performance. The study concluded that principals' monitoring of instructional practices (mean=3.5, SD=1.2) significantly influenced performance in schools. It recommended that the Ministry of Education should organise training for principals to improve their skills of monitoring assessment.enassessmentteaching and learningoutcomeArticle