The study investigated the effect of Activity and conventional teaching methods on students‟ performance and retention in Agricultural Science in Senior Secondary Schools in Kaduna State Nigeria. Five objectives were used to carry out the study. These include to determine the effect of Activity-Based method of teaching on students‟ performance in Agricultural science in senior secondary schools in Kaduna State, ascertain the retention ability of students‟ taught Agricultural Science using Activity-Based method and those taught using Conventional teaching method in Senior Secondary Schools in Kaduna State, The objectives were transformed into five corresponding research question and hypotheses. The research adopted the quasi-experimental design of pre-test, post-test. The sample size for the study comprised 244 SSII Agricultural Science students‟ selected using purposive sampling techniques. The instrument used for data collection in the study was a structured Agricultural Science performance test (ASPT) designed by the researcher. The instrument consisted of forty-five (45) multiple-choice test items. The drafted instrument was validated by the researcher supervisors and two experienced Agricultural Science experts one from Amadu Bello University and Kaduna State Ministry of Education. The validated instrument was pilot tested using test-retest, the data collected from the pilot study were analysed using Pearson product-moment correlation coefficient and a reliability coefficient of 0.70 was obtained. The data collected were subjected to statistical analysis using both descriptive and inferential statistical techniques. Frequency and percentage were used to analyse the biodata of the respondents‟, while the mean and standard deviation was used to answer the research questions. Independent sample t-test was used to test the hypotheses at 0.05 level of significance. Findings from the study among others revealed that the performance of students‟ taught Agricultural Science using Activity-Based teaching method was significantly better than those taught using conventional teaching method, that the students‟ taught Agricultural Science using Activity-Based teaching method retain the learned concepts for a long time than their counterparts taught using conventional method, The study concluded that Activity-Based method of teaching has a facilitating effect on the performance of students. The following recommendations were made among others, that teachers of Agricultural Science should explore Activity-Based method to their advantage in enhancing effectiveness in the classroom teaching and consequently engender student better performance, the teaching style by Agricultural Science teachers should be based on guiding, directing and facilitating while students‟ should do the real work by themselves. This would enable them to discover new ideas and skills in solving problems.