Second International Enzymes in the Environment Research Coordination Network Workshop: Incorporating Enzymes and Microbial Physiology Into Biogeochemical Models; Colorado State University, Fort Collins, Colorado, 15–18 May 2012 Recent studies have provided new insights into the factors controlling the production and activities of extracellular enzymes, the proximate agents of organic matter decomposition. Enzymes and other aspects of microbial physiology have been incorporated into simple models but have not yet been explicitly incorporated into biogeochemical models capable of predicting fluxes of carbon and nutrients. One reason for this is that empirical data collected at one or few locations and time points do not meet the needs of modelers attempting to integrate across spatial and temporal scales. Furthermore, there is a disconnect between the types of data measured in observational and experimental studies and the data needed to parameterize biogeochemical models. For example, the most common approach is to measure maximum potential enzyme activities in laboratory assays, whereas models require measurements of enzyme kinetics when substrate is limiting.