The study titled Assessments of effects of activity-based and brainstorming instructions on students' performance in Islamic Studies in Junior Secondary Schools in Kaduna state, Nigeria. The study was conducted with five objectives which include: determine the effects of activity-based instruction on students' performance in Islamic studies as compared to the Conventional method in junior secondary schools in Kaduna state;examine the effects of brainstorming instruction on students' performance in Islamic studies as compared to the Conventional method in junior secondary schools in Kaduna state; and determine the effects of activity-based and brainstorming instruction on students' performance in Islamic studies as compared to the Conventional method in junior secondary schools in Kaduna state. Quasi-experimental research design was used in the study. The total population was 40,490 out of which six (6) intact classes of Zaria and Soba local governments of two hundred and forty two (242) students were used as sample size. A researcher-made test called "Islamic Studies Achievement Test" (ISAT) was used for data collection. The instrument was pilot tested with the reliability index at 0.88. Mean and standard deviation were used to analyses the research questions. Hypotheses 1 and 2 were tested using t-test, while hypotheses 3, 4 and 5 were analyzed using ANOVA at 0.05 alpha level of significance. Findings revealed that Students taught Islamic Studies using activity-based instruction performed significantly better than those taught with conventional method in Junior Secondary Schools in Kaduna State. Performance of students taught Islamic Studies using brainstorming instruction was far better than those taught using conventional method in Junior Secondary Schools in Kaduna State. In the light of the findings from this study, it was recommended that;Islamic Studies Teachers should promote activity-based instruction as it will encourage and motivate students to participate actively in classroom. Brainstorming instruction should be adopted by Islamic Studies teachers since it improved faculty of reasoning and thinking during teaching and learning, workshops, seminars, conferences and enlightenment should be organized from time to time for Islamic studies teachers in junior secondary schools in Kaduna stated so as to keep abreast of modern or innovative teaching instruction such as activity-based and brainstorming instruction