This is very much a personal view of what I think are some of the most important unanswered questions in ecology. That is, these are the questions that I expect will be high on the research agenda over the coming century. The list is organized hierarchically, beginning with questions at the level of individual populations, and progressing through interacting populations to entire communities or ecosystems. I will try to guess both at possible advances in basic knowledge and at potential applications. The only thing that is certain about this view of the future is that much of it will surely turn out to be wrong, and many of the most interesting future developments will be quite unforeseen.