This part of ISO 17512 specifies a rapid screening method for evaluating the habitat function of soils and the influence of contaminants and chemicals on earthworm behaviour. The sublethal test is a rapid method that reflects the bioavailability of contaminant mixtures in natural soils and substances spiked into soils to Eisenia fetida and Eisenia andrei. The avoidance behaviour of the worms is the measurement endpoint of the test. This test is not intended to replace the earthworm reproduction test. Two different designs (a two section unit and a six section unit) have been developed and successfully applied. Both designs are applicable to either single-concentration (e.g. for assessing the quality of a field soil) or multi-concentration (e.g. for assessing the toxicity of a spiked chemical) tests. In both cases, the earthworms are allowed to make the initial choice on which compartment, control and a treatment [in the two section test vessel between right and left side; in the six section test vessel between the (3 + 3) alternating compartments], to enter.