Considerable expenditure on human resource development (HRD) has not necessarily resulted in a significant impact on organizational performance, and research suggests that the failure to transfer learning may be an important explanation. The search for factors affecting transfer has been extensive, as shown in Grossman and Salas's article in this issue, but, as they also show, more research is needed. The purpose of the present study is to ascertain the views of HRD practitioners (in Ireland) about the factors that they believe are relevant to the transfer of learning in the workplace. The aim is to discover whether practitioners have identified potential factors which researchers have not explored or not explored sufficiently. This group of practitioners was chosen because of the considerable control they wield over significant tranches of organizational resources. The method first involved engagement with 28 senior HRD practitioners in a workshop setting to create a transfer inventory based on their expert opinion. The initial inventory was then responded to online by a group of 314 practitioners indicating the relevance of the items to the question of transfer. Factor analysis was used to achieve parsimony among items, and 21 potential factors were identified. This study focused on the 15 factors adjudged by practitioners to be most relevant. It is concluded that trainer effectiveness, organizational linkage and training event climate, all deemed relevant by practitioners, may justify further research.