The Arnold Arboretum is a public "tree museum" that sits on more than 300 acres of parkland in Boston. Like many public parks, the arboretum uses a percentage of its funding to provide nature education for adults and schoolchildren, facilitated by trained volunteer docents. One such effort is the Head Start-Arboretum project, which provides children with authentic experiences with nature that gives context to their school life science activities. This article describes how the authors used this opportunity to get their preschoolers outside--and into science. (Contains 1 figure.)