Cover: Researchers with the Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO) and the Multi-Agency Rocky Intertidal Network (MARINe) sample community structure in the rocky intertidal. These surveys, conducted at over 200 sites since 1992, characterize the geographic and interannual variation of rocky intertidal communities from Mexico to Alaska. In addition to identifying environmental drivers and species interactions that influence these patterns of variation, these surveys have informed how rocky intertidal ecosystems respond to climate variability (e.g., El Niño and La Niña events), anthropogenic perturbations (e.g., oil spills), and the design and evaluation of marine protected areas. Long-term ecological and environmental studies such as this one are discussed in an article in this issue by Brent Hughes and his colleagues. Photograph: Mark Carr.