This study investigated the Impact of Science-Technology-Society (STS) Instruction on Performance and Retention of EcologyConcepts among Slow Learners in Secondary Schools inKaduna. The study employed apre-test, posttest, post posttest quasi experimental design. The population consisted of 190 SS2 science students consisting of 105 males and 85 females. Two schools were purposively selected and were randomly assigned control and experimental groups using a toss of a coin. The slow learners were selected using three years consecutive exam results of students who obtained below a score of 50 marks in biology (Ofonime, 2007). The subjects were taught for six weeks using STS Instruction and Lecture Method for the experimental and control groups respectively. The instrument used for thepre-test, posttest, and post posttest was the Biology Performance Test (BPT). The objectives of this study were to: (i) determine the effect of STS Instructional Strategy on students' academic performance in S.S.S biology; (ii) investigate if the use of STS Instructional Strategy enhanced retention of learned ecological concepts among senior secondary students (iii) assess if gender differences existed between performance scores of slow learners taught using STS Instructional Strategy.Three research questions were raised with corresponding hypotheses stated. The null hypotheses were tested using t-test statistics with level of significance at P ≤ 0.05.The major findings from the study indicated that slow learners exposed to STS Instructional Strategy in learning ecology concepts performed significantly betterthan those exposed to lecture method. Slow learners taught ecological concepts using STS Instruction retainedmore ecological concepts than those taught using lecture method. Lastly, there was no significant difference in the mean academic scores of male and female slow learners taught ecological concepts using STS Instruction. Based on the findings of the research it was recommended that STS Instruction is an alternative teaching strategy to attain the goal of learning and teaching of slow learners. It can therefore be used in teaching to help slow learners retain knowledge better. In conclusion this study yielded positive results using STS Instructional Strategy on the performance and retention of ecological concepts taught to slow learners in selected public Senior Secondary Schools in Kaduna, Nigeria.