The present invention relates to a conditioning and detergent cosmetic composition for keratinous substances comprising, in an aqueous medium: (A) at least one non-volatile vegetable oil, (B) at least one anionic sulphate surface-active agent, (C) at least one non-ionic alkyl glycoside surface-active agent, the (B)/(C) ratio by weight being less than or equal to 2:1. Use in simultaneously caring for and washing keratinous substances, in particular the hair.
