The last 10 years have seen an increase in the number of studies investigating the effects of biodiversity on ecosystem functioning. While many of these studies have found a decrease in a particular ecosystem function with decreasing biodiversity, most of them have investigated plant productivity or another function directly related to primary productivity. This bias toward the producer level hinders the generalizations that can be made about the biodiversity–ecosystem functioning relationship and it also possibly affected the conclusions drawn in recent meta-analyses (e.g. Balvanera et al. 2006, Ecology Letters 9: 1146-1156 and Cardinale et al. 2006, Nature, 443: 989-992). More recently, studies have gone beyond productivity and plant-related ecosystem processes and investigated the effects of biodiversity on a larger array of ecosystem processes. While this has increased our knowledge of the biodiversity–function relationship considerably, most analyses still consider only one ecosystem process at a time. In the real landscape, however, ecosystems are valued because they provide various services simultaneously and ecologists should understand how biodiversity relates to ecosystem “multifunctionality.” The concept of multifunctionality is also now prevalent in agriculture where farmers are expected to not only optimize production of goods, but also other ecosystem functions such as soil nutrient retention, carbon storage, or the preservation of beneficial insect diversity. Looking beyond single variables and consider the multifunctionality of biodiversity is not simple as there is no prescribed way in which functions should be combined in the analysis of the importance of biodiversity. An important first step in the analysis of multifunctionality was made in a recent paper by Hector and Bagchi (2007, Nature, 448, 188-191) and such approaches need to be extended to advance our understanding of the influence of various components of biodiversity on multiple ecosystem functions further. In our session, theoretical and empirical approaches to the analysis of the multifunctionality of biodiversity will be presented and discussed. We aim at a mixture of talks that focus either on the mathematical or statistical ways to understand multifunctionality (Schmid, Hector, Cardinale, Gamfeldt, Balvanera) or present results of biodiversity experiments where many functions were measured simultaneously (Allan, Tilman). In addition, a number of talks will consider results from real landscapes where the role of biodiversity for various ecosystem functions has been investigated empirically, for agricultural landscapes in Central Europe (Tscharntke, Pywell) or a rain forest in Brazil (Fonseca).