Nigeria has since integrated EE concepts into all subjects at the primary and secondary levels of education. However, the major dilemma faced by Nigerian teachers is how to effectively teach these concepts to develop appropriate environment-related attitudes and values in the learners. Most classrooms in Nigeria are still characterized by teacher dominated strategies which may not be able to foster appropriate environmental attitudes. This study therefore explored the use of participatory learning strategies in teaching environmental education concepts. The study further examined the interactive influence of group size and academic ability of students on the dependent measures. The assumption for trying these strategies was based on the premise that EE is not just about telling, but about knowing and acting. Three hundred and sixty Senior Secondary II students drawn from nine schools constituted the subjects for the study. The students were taught the selected EE concepts using the full and quasi-participatory strategies with the conventional lecture as the control. The Environmental Attitude Questionnaire constituted the only instrument used for data collection. Four hypotheses were tested at p<0.05 level of significance. Findings from the study show that students taught EE concepts using the participatory approaches developed a more positive attitude to the environment, with those in the full participatory group having the best attitude scores. The results also indicate that students who worked in the small groups demonstrated a more favourable attitude. The participatory approach affords the students to learn and work more effectively with others which made them more sensitive to the necessity of having a descent respect for the opinions of others and be more sensitive to their environment. The implications of these findings for the teaching of EE concepts were discussed. On the whole, it was suggested that the participatory group learning strategies could be a more viable alternative to the traditional conventional methods of classroom teaching.