The February joint AGU/ASLO meeting in San Antonio brought together scientists from a wide range of oceanographic and limnological subdisciplines. One of the implicit themes in many of the sessions was the importance of mesoscale processes (space scales: 10–1000 km; time scales: days to a few years) and the interdisciplinary nature of the studies needed to understand them. Several sessions addressed mesoscale phenomena directly; one, organized by John Steel of Woods Hole Oceanographic Institution, focused on the relations between biological and physical mesoscale processes. This article is adapted from the introductory talk to Steele's mesoscale session. The talk attempted to give a general pverview of some of the less emphasized connections between physical and biological mesoscale processes and the relationships between them, larger- and smaller-scale phenomena, and the strategies and instrumentation used to study such processes.