<p>The ability to flexibly adapt to the demands of a stressful situation is a key factor in successful coping. Appropriate coping is of critical importance in artificial environments, which may include novel and potentially stressful situations. Being able to inhibit immediate but counterproductive reactions, and thus exert inhibitory control, might allow to better adapt to the environment. Horses are required to flexibly adapt to various housing conditions and training techniques; however, not all horses successfully cope as evidenced by the prevalence of stereotypical behaviours. We tested 31 mares in an inhibitory control test battery (A-not-B detour test, delay of gratification test, reversal learning test) and assessed their behavioural and stress-physiological reaction during two husbandry conditions (social isolation and food omission). All three inhibition tests revealed behaviours indicative of inhibitory control, which could be well represented by four components resulting from a PCA (inhibition, indecisiveness, learning capacity, flexibility). The variation in coping behaviour could be captured by six components (nervousness, stress, anticipation, reactivity, oral motivation, vigilance). We found that reactivity and vigilance were positively related to inhibition. Reactivity was additionally negatively related to indecisiveness and positively related to flexibility. These findings may suggest that inhibitory control is an underlying mechanism involved in flexible responding, which may ultimately facilitate successful coping.</p>