This study examined the use of behavioural complexity as a potential to assess the stressfulness of an animal’s environment. Chickens were videotaped for 0.5 hr periods and the changes in behaviour analysed to yield a complexity value. This technique was then used to determine the effects on behavioural complexity when birds were exposed to different potential stressors. Differences were found in the behavioural complexity of locomotor and resting behaviours when birds were exposed to food restriction, social crowding through the addition of more birds, and when sand was provided. The direction of these changes was not consistent for all stressors, however, the authors conclude that behavioural complexity is a non-invasive means to assess different housing conditions.