Education is a lifelong endeavor; the public learns in many places and contexts, for a diversity of reasons, throughout their lives. During the past couple of decades, there has been a growing awareness that free-choice learning experiences - learning experiences where the learner exercises a large degree of choice and control over the what, when and why of learning - play a major role in lifelong learning. Worldwide, most environmental learning is not acquired in school, but outside of school through free-choice learning experiences. Included in this article are brief overviews of environmental learning, the nature of learning, the educational infrastructure, and free-choice learning as a term. This article provides a framework for thinking about free-choice environmental learning and sets the stage for thinking about the other articles in this special issue.