The first batch of graduates in the country under the K-12 curriculum graduated in 2018. Thus, a call for an evaluation of students' acquired competency is essential. That's why, there is a need for the construction of assessment tools. In this study, a valid, reliable, and item quality achievement test in General Mathematics was developed. Eight experts examined the test for its improvement and refinement. The test was pilot-tested to 425 senior high school students, was item analyzed, and was subjected to a reliability test. Forty questions were included in the final form of the test. The average item difficulty was 0.40, which means intermediate while the average item distinctiveness was 0.34, which signifies well items. Moreover, the reliability coefficient of the test was 0.84, which indicates that the items of the constructed test have acceptable value for internal consistency. The result suggests that the developed test is an excellent tool for classroom assessment.