Soil organisms are essential for the functioning of agrosystems, especially in the process of litter decomposition. Litterbags constitute one common way to assess litter decomposition and to investigate the role of the different groups of soil organisms in the decay activity. However, there is currently no standardized litterbag protocol to measure the effects of soil organisms on litter decomposition. Furthermore, litterbag studies remain scarce in agrosystems and little information is available about the influence of different groups of soil organisms depending on agricultural practices. The development of cropping systems that rely on high soil biodiversity and fertility however requires a detailed understanding of these processes. In order to address this need and to have an overview of the existing protocols, we conducted a review on litterbag experiments in annually cropped soils. We collected information on the experimental design (e.g. duration, number of replicates), litterbags (e.g. size, mesh), climate, soil type, standing crop, enclosed litter (e.g. litter type, quality) and methods used to characterize organic matter decomposition and soil organisms. The effects of soil organisms of different size classes (meso- and macrofauna) was assessed with a meta-analysis performed on studies using litterbags of different mesh sizes. The general effect size of soil macrofauna, mesofauna (in addition to soil microorganisms) and of their combination was assessed with a three-level random-effect model accounting for the random effect at the study level. This effect was compared for subgroups based on climate, soil, standing crop, agricultural system and litter type as categorical factors, and for depth of bags, duration of the experiment and size of litter pieces as continuous factors. Macrofauna, mesofauna and the combination of both were found to significantly increase litter decomposition. Surprisingly, meso- and macrofauna contributed equally to litter decomposition and their effects were not additive (when comparing the role of meso- and macrofauna independently and simultaneously). These effects tend to be influenced by various factors: climate, soil, standing crop and agricultural system for macrofauna; standing crop and litter type for mesofauna; and soil, standing crop and litter type for their combined effects. Multi-mesh litterbag experiments showed that even in soils with high disturbances, soil organisms of several size classes have a significant impact on organic matter decomposition. While this study showed that both soil macrofauna and mesofauna increased litter decomposition in annual cropping systems, there are still numerous gaps in our knowledge of the impacts of the agronomic (e.g. cropping system, practices, crop type) and environmental contexts (e.g. climates, soils). Forecasting future studies, we provide guidelines to develop a standard litterbag protocol adapted to the specificities of annually cropped soils.