The study investigated the relative effectiveness of framing and team assisted individualised (TAI) instructional strategies on the attitudes toward mathematics of 350 senior secondary school year two Nigerian students. The moderating effects of gender and style of categorisation were also examined. The study adopted pre-test and post-test control group quasiexperimental design using a 3×2×2 factorial matrix with two experimental groups and one control group. Seven null hypotheses were tested and two research instruments, Attitudes toward Mathematics Inventory (ATMI) and Style of Categorization Test (SCT) were administered on the sample and data gathered were analysed, using analysis of covariance and Scheffe Test. The results indicated significant main effects of treatment and gender in which the participants exposed to the TAI strategy had the highest post-treatment attitudes mean score and male students had stronger attitudes toward mathematics than their female counterparts. There was no significant main effect of style of categorisation on students' attitudes toward mathematics. While there were significant twoways interaction effects of treatment and style of categorization and gender and style of categorisation on students' attitudes toward mathematics, there was no significant interaction effect of treatment and gender on students' attitudes toward mathematics. In addition, the three-way interaction effect of treatment, gender, and style of categorization on students' attitudes toward mathematics was significant. The findings revealed that TAI and framing strategies were more effective in promoting students' attitudes toward mathematics. Thus, these instructional strategies could be used to positively change students' attitudes toward mathematics.