In 1984, the Connecticut General Assembly established mastery tests in mathematics and language arts (listening, reading, and writing skills) for grades 4, 6, and 8. A criterion-referenced test was considered most appropriate for identifying the strengths and weaknesses of every student. The specific skills to be mastered were identified by Connecticut educators. The Grade 6 Mastery Test results for 1990 are provided. The Grade 6 Mathematics Test assesses 36 specific objectives in conceptual understanding, computational skills, problem solving/applications, and measurement/geometry. The Language Arts Advisory Committee recommended a 112-item test for grade 6 covering reading/listening and writing/study skills. In 1990, sixth-graders mastered an average of 24.6 of 36 objectives, a slight improvement from the preceding year's figure of 24.1. In language arts, sixth-graders mastered an average of 8.1 of the 11 objectives tested, also an improvement over the preceding year's figure of 7.4. Writing scores decreased slightly, and reading scores remained unchanged. Test equating procedures used for comparing the scores are discussed, and test administration and scoring practices are described. Results for 1986 through 1990 are summarized. Fourteen charts present student achievement data. Thirteen appendices present test construction practices, specific objectives, the remedial standard setting process and committees, an overview of holistic scoring and marker papers for holistic scoring, the analytic rating guide and marker papers for analytic scoring, sample mastery test score reports, fall 1990 state by district reports in mathematics and language arts, the percentage of students meeting the statewide goal in each content area by district on the Connecticut Mastery Test, types of community classifications, education reference group descriptions, and student participation rates. (SLD)