Purpose: Participatory extension, specifically farm discussion groups, has become a very popular form of agricultural extension in Ireland. The purpose of this article is to assess its effectiveness in promoting the adoption of new technologies and improving farm profit. Design/Methodology/Approach: Following a review of the background and theory of discussion groups, statistical analyses are conducted. Two discrete choice models are estimated. The first assesses the factors associated with participation in discussion groups. The second model controls for these factors while testing the effect of discussion group membership on technology adoption. A multiple regression is used to estimate the effect of group membership on farm profit. Findings: The results of the analysis show that selection bias is an issue with this form of extension. Typically discussion group members tend to have larger farming operations in more advantaged regions than those not participating in the groups. Even when these advantages are controlled for, discussion group membership still has a positive impact on technology adoption and profit levels. Practical Implications: The results of this analysis have implications for those involved in designing and delivering discussion groups. There is evidence to support that discussion group membership increases technology adoption and farm profit, however, greater efforts could be made to include more diverse cohorts of farmers into these groups. Originality/Value: To the best of the authors' knowledge, this is the first article that aims to empirically estimate the effect of discussion group membership on technology adoption and farm profit. (Contains 1 figure, 7 tables and 2 notes.)