Context: Cereal-legume intercropping offers potential for the sustainable intensification of annual cropping systems. Crop models can support the evaluation of agronomic and environmental benefits of intercropping. However, to be effective, they must capture interspecific interactions during the growing season, a challenging task in tropical systems where such models remain largely untested. Objective: This study assessed the ability of the STICS model to simulate cereal-cowpea intercropping productivity and the final outcomes of interspecific interactions occurring over the cropping season under tropical semi-arid conditions. Methods: Data from four experimental sites in West Africa, including sorghum, millet, and cowpea grown in sole cropping, were used for parameter calibration. STICS was evaluated using intercropping measurements. To analyse interspecific interactions in intercropping with contrasted sowing patterns, we adapted the partial Land Equivalent Ratio (pLER). Specifically, we corrected the pLER of each crop by dividing it by the ratio of the number of plants per m² in intercropping to the number of plants per m² in sole cropping (pLERcor.dens). This adjustment allowed us to evaluate interactions at the plant level. Four situations were identified: i) cereal and legume pLERcor.dens <¿1, indicating that competition outweighed complementarity, compensation, and cooperation or facilitation effects, i.e., productivity of both crops was reduced in intercropping, ii) cereal pLERcor.dens >¿1 and legume pLERcor.dens <¿1, indicating that the cereal suppressed legume growth, iii) cereal pLERcor.dens <¿1 and legume pLERcor.dens >¿1, indicating that legume suppressed cereal growth and iv) cereal and legume pLERcor.dens >¿1, indicating that the productivity of both crops was enhanced by intercropping. Results: STICS simulated cereal aboveground biomass and grain yield in intercropping with a higher model efficiency (Ef) than 0.48 and cowpea aboveground biomass with