Technical Abstract: Cross-scale interactions occur either when fine-scale processes influence a broad spatial extent or a long time period, or when broad-scale drivers interact with fine-scale processes to determine system dynamics. Cross-scale interactions are increasing recognized as having important influences on ecosystem processes, yet, they pose formidable challenges for understanding and forecasting ecosystem dynamics. In this introduction to the special feature, ‘Cross-scale interactions and pattern-process relations”, we provide a synthetic framework for understanding the causes and consequences of cross-scale interactions. Our framework focuses on the importance of transfer processes and spatial heterogeneity at intermediate scales in linking fine- and broad-scale patterns and processes. Transfer processes and spatial heterogeneity can either amplify or attenuate system response to broad-scale patterns and processes. Providing a framework to explain cross-scale interactions is an important step in improving our understanding and ability to predict the impacts of propagating events and to ameliorate these impacts through proactive measures.