This paper proposes that despite the anticipated benefits of classroom research for improved instruction, there are identifiable factors that can interfere with its effectiveness. Examples are drawn from three research projects, undertaken in English-as-a-Second-Language instructional settings. First, the steps in the classroom research process are outlined. Then for each case, the evolution of the project is described, problems are noted, and attempts to remedy them are examined. The cases involved professional development projects for secondary and postsecondary language teachers. It is concluded that in each instance, some of these things happened to prevent change: (1) teachers were not given recognition or time off for doing research; (2) the agenda was controlled by the administration; (3) the agenda was subverted from within by teachers who wanted to bolster their own position within the political context in which they worked; (4) teachers lacked the technical skill and knowledge to conceptualize and operationalize their research interests; and (5) doing research got in the way of teaching; (6) there was a secondary agenda concerning curriculum development; and (7) teachers feared that involvement in classroom research would be used against them. A series of recommendations is made for maximizing chances of success. (MSE)