The study aimed to find out the effect of HIV & AIDS capacity building programme on pupils’ HIV & AIDS knowledge and positive attitude in North Central Nigeria. The study was guided by two research purposes with two corresponding research questions and hypotheses. The study adopted quasi experimental (non – equivalent control groups) research design. The population for the study was made up of 3,049,810 upper public primary school teachers in the Zone. A sample of 400 public primary school pupils, was drawn from 40 primary schools using non-proportionate stratified simple random sampling techniques. The instruments used for data collection were HIV& AIDS Knowledge Test (PHAKT) and Pupils HIV & AIDS Attitude Scale (PHAAS). Data collected were analyzed using mean and standard deviations to answer the research questions, analysis of covariance (ANCOVA) was used to test the null hypotheses. The findings of the study showed that teachers’ exposure to HIV & AIDS capacity building programme increased Pupils’ HIV & AIDS Knowledge; and positive attitudes towards preventing the spread of HIV & AIDS; that there was significant difference in HIV & AIDS knowledge scores of pupils taught by teachers exposed to HIV & AIDS Capacity Building Programme (HACBP) and those that were not. Also, there was a significant difference in HIV & AIDS positive attitude scores of pupils taught by teachers exposed to HACBP and those that were not. Based on the findings and implications of the study, it was recommended among others that primary school teachers should be exposed to HACBP.