Investigating the effects of cooperative learning as an instructional strategy for teaching basic science and mathematics to junior secondary school students in Katsina state was the focus of this study. Equally, it also looked at how gender affect students' performance and attitude in basic science and mathematics when cooperative learning was used as an instructional strategy. Quasi-experimental design was used in the study with 240 students as sample selected purposively. Cooperative Learning Guide (CLG), Basic Science and Mathematics Performance Test (BSMPT) and Students' Attitude to Science and Mathematics Questionnaire (SASMQ) were used as instruments for data collection. Reliability indices of 0.78 for BSMPT and 0.79 for SASMQ were obtained using split haft method and Cronbach alpha respectively. Analysis of the data was done using, t-test and Pearson Product Moment Correlation Co-efficient. Findings of the study revealed that students taught using cooperative learning strategy performed higher than those taught using inquiry learning strategy; there was an insignificant difference in performance between the male and female students in the cooperative learning group. The students in cooperative learning group show a more positive attitude towards basic science and mathematics than those in inquiry classroom learning. On the bases of these findings, it was recommended that cooperative learning strategy be adopted by all secondary school Basic Science and Mathematics teachers as an effective learning strategy in order to improve students' performance and positive attitude towards science and mathematic