Research in psychology of religion and spirituality has roots stretching back into the19th century, however only recently has it begun researching atheists and other nonreligious individuals. While informative, these investigations have yet to build or identify psychologically meaningful constructs from nonreligion that are not contaminated by, or situated within, a system of theistic propositions. Explorations that focus on purely negative identities (e.g., not a theist) may fail to capture much of what is psychologically interesting and informative about this demographic. Atheism is interesting juxtaposed against the background of world-wide belief, but nonreligious worldviews are multidimensional, complex, and worthy of investigation in their own right. Building on that fact, this special issue challenged scholars to explore nonreligious worldviews as full-fledged constructs and to develop measurement instruments which capture different facets of nonreligious experience. Before introducing a collection of 9 articles that responded to this challenge in unique ways, we reflect on the estimated prevalence of atheist and nonreligious individuals, discuss misconceptions associated with nonreligion, note how investigating secular worldviews is critical for the psychology of religion, and provide a brief overview of the diversity of nonreligion.