There is growing recognition of the significance of learning within debates about sustainable development. Within the field of environmental education research, however, there has been insufficient attention given to questions of learners and learning. In the light of this situation, this paper reports findings from two studies (one in England, the other in Sweden) that focused specifically on learners' experiences of and responses to environmental curricula in secondary school and higher education. Three kinds of learning challenges that can be experienced by students on environmental education courses are outlined and discussed. The main purpose of the paper is to highlight the complexity of the learning experience within environmental education and to draw attention to the need for improved research-based understandings of environmental learning processes. (Contains 1 figure.)