We introduce a collection of articles that proposes conceptual and methodological tools to advance the integrated study of ecological boundaries. A number of studies are germane to understanding the structure and function of boundaries over a wide array of ecological systems and scales. However, these studies have not been unified in a consistent theoretical framework. To integrate these seemingly disparate studies and to advance future research on boundaries, these articles present a common conceptual framework, a classification of the different types of boundaries and their potential functions, and statistical and modeling approaches that can be applied to a wide range of systems, processes, and scales. We summarize the themes that emerge from these articles and suggest questions to guide future research.