This study investigated"Efficacy of Concept-Mapping Instructional Strategy on Retention and Performance among Basic Science Students with Varied Abilities in Zaria, Kaduna, Nigeria". A sample of 120 JSS students were randomly selected from the population of 3,729 students. The sample emerged after pretesting 1,327 students who were randomly selected from the six study schools. They were further categorized into high, medium and low ability on the basis of their performance in the pretest. The three experimental groups were taught the concepts of work, energy and power using concept mapping teaching strategy, while the control group were taught same concepts using lecture method. Pretest; post test and postpost test data generated were analyzed to determine whether the two groups are significantly different in their ability. Three null hypotheses were tested using ANOVA statistic at p-value 0.05 and the following major findings were made: Students exposed to concept mapping teaching strategy achieved and retained the basic science conceptssignificantly higher than their counterparts exposed to lecture method. Also the high medium and low ability level (HML) students in the experimental group achieved better than their counterparts in the control group. There was no significant difference in academic performance of male and female students exposed to concept mapping teaching strategy and lecture method. It is concluded that concept mapping teaching strategy employed by teachers in science teaching has direct bearing on students? performance as students of all ability (HML) exposed to concept mapping teaching strategy achieved and retained learned basic science concepts significantly higher than those taught same concepts using conventional lecture method. Both boys and girls benefitted equally on their exposure to concept mapping teaching strategy. In conclusion concept mapping strategy is an effective strategy for teaching basic science concepts in junior secondary schools and its gender friendly. On the basis of these findings, some recommendations were ma