This document describes a method to assess the bioaccumulation of chemicals in snails, i.e. concentrations of metal(loid)s (ME) or organic compounds (e.g. PAHs and PCBs) accumulated in their tissues. This document presents how to prepare snails for caging in situ for 28 days, the in situ test design and then how to collect and prepare the snails until conservation and further analysis. If a kinetic study of accumulation is necessary, sampling of snails at different time-points during exposure is possible as well (Gimbert et al., 2008a; Pauget et al., 2013; Mariet et al., 2017) This standard excludes analytical methods: preparation (extraction and mineralization) of the samples and quantification of chemicals. These are not in the scope of the present document. The method is applicable for soils under different uses (agricultural, industrial, residential, forests, before and after remediation, on potentially contaminated sites, etc.) and waste materials (de Vaufleury, 2015; Bourioug et al., 2015), and should be preferably used on soil with vegetation and/or humus cover. The method is applicable subject to certain limits of temperature (frost-free period, i.e. mainly from April to October in temperate region). Optionally (Annex A) the method can be used in the laboratory to evaluate the accumulation of contaminants (and optionally the Sum of Excess of Transfer (SET) index for ME, PAH, PCB) of snails exposed only to soil.