The paper investigated on teachers’ awareness and utilization of standard scores in assessment of students’ mathematics performance in secondary schools in Rivers State. Two research questions and two hypotheses guided the study. The design of the study is descriptive design. A sample of fifty-four (54) mathematics teachers was drawn from the population of 12,342 teachers in the locale of the study through multistage sampling procedures. An instrument titled Standard Score Awareness and Utilization Questionnaire (SSAUQ) developed by the researchers was used for data collection. Factor analysis was used to determine the validity of SSAUQ while Cronbach alpha was used to establish a reliability index of 0.89 indicating that the instrument was reliable. Mean and standard deviation were used to answer the research questions while two-way analysis of variance was used to test the hypotheses at 0.05 alpha level. The results revealed that there is no significant interaction difference in the level of awareness of standard scores in mathematics assessment by teachers based on their location, school type as well as gender. Also, there is no significant interaction difference in the level of utilization of standard scores in mathematics assessment by teachers based on their location, school type as well as gender. Based on the findings, it was recommended among others that Government should from time to time organize conferences, workshops and seminars for teachers concerning use of standard scores in assessing students’ performance.