The EFSA Panel on Plant Health performed a pest categorisation of Resseliella maxima (Diptera: Cecidomyiidae), the soybean gall midge, for the EU. This midge was first described in 2018 and is widespread in north-western United States. It is not listed in Annex II of Commission Implementing Regulation (EU) 2019/2072. Larvae feed on and develop in soybean (Glycine max, Fabaceae), and possibly in two other Fabaceae, sweet clover (Melilotus officinalis) and alfalfa/lucerne (Medicago sativa). Feeding damage results in dark brown or black areas on the stems which become weak and can break near the soil; heavy infestations can cause plant death. R. maxima adults live only a few days and adult females lay eggs within 24 h after emergence. Larvae of R. maxima overwinter in the soil as third instars in silken cocoons. The main natural dispersal stage is the adult, which can fly. Freshly cut host plants for animal feed contaminated with larvae provide a potential pathway for entry into the EU. However, there is great uncertainty as to whether such plants are imported from USA states where R. maxima occurs. Climatic conditions and host availability in central-western EU MS are favourable for outdoor establishment. Phytosanitary measures are available to reduce the likelihood of entry and spread. Except for the uncertainty concerning the likelihood of entry, R. maxima satisfies the other criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest.