A model for bivalve growth was developed and the results were tested against field observations. The model is based on the Dynamic Energy Budget (DEB) theory and includes an extension of the standard DEB model to cope with changing food quantity and quality. At 4 different locations in the North Sea (Wadden Sea, Sean Gas Field, Oyster Grounds and Dogger Bank), labelled blue mussels Mytilus edulis were kept under natural conditions. Shell length was repeatedly measured for each mussel during the experiment, and dry weight was determined at the end of the experiment for some of the mussels. Temperature, salinity, chlorophyll concentration and Secchi depth (at the Wadden Sea location) were measured next to the experimental sites. Model performance was evaluated by comparing predicted and measured shell length, dry weight and growth at each location for each individual, without changing parameter values that were previously obtained from independent studies. The results show that the model was able to reproduce the main patterns of the observations, implying that the main metabolic processes at the individual level are well described. © Inter-Research 2012 · www.int-res.com.