The conventional teaching of geography in Nigeria today has not brought about improved students’ performance in the subject. Hence, there is the need to expose students to other strategies that can make them improve their performance in map reading and interpretation. This is why the study is conceptualised to determine the relative effects of cooperative and individualistic learning strategies on secondary school students’ achievement in map reading and interpretation. The possible mediating influence of numerical ability and gender were also investigated. The study employs pretest, posttest, control group, quasi-experimental research design. Subjects comprised 164 senior secondary II (SSII) geography students, made up of 109 boys and 55 girls, drawn from three secondary schools in Ilesa East and west Local Government Areas of Osun state, south-west, Nigeria. Three instruments were used to collect the requisite data — Numerical Ability Test (NAT), Map Reading and Interpretation Achievement Test (MARIAT) and Treatment Implementation Guides on Cooperative, Individualistic and the Conventional learning strategies. Three null hypotheses were formulated and tested at 0.05 level of significance. Data collected were analysed using ANCOVA, Multiple Classification Analysis (MCA) and Scheffe Post-hoc Analysis. Treatment had a significant main effect on students’ map reading and interpretation [F (2, 163) = 35.181, p<. 05). Cooperative learning strategy was the most effective for the dependent measure. It was also found that numerical ability had a significant main effect on the dependent measure, with high numerical ability subjects performing better than their average and low ability counterparts. The study demonstrates the efficacy of the cooperative learning strategy on students’ achievement in map reading and interpretation, taken into consideration their numerical abilities and gender