I consider a definition of (causal) explanation that is a variant of one Judea Pearl and I gave. The definition is based on the notion of actual cause. Essentially, an explanation is a fact that is not known for certain but, if found to be true, would constitute an actual cause of the fact to be explained, regardless of the agent's initial uncertainty. I show that the definition handles well a number of problematic examples from the literature, and discuss various notions of partial explanation.