Summary1. There is growing evidence that dispersal is highly phenotypically plastic, i.e. that dispersal is condition-dependent. In the common lizard, dispersal has even been shown to be in¯uenced by the maternal environment during pregnancy. Juveniles in good condition or issued from mothers in good condition disperse earlier or in higher numbers. 2. We hypothesized that plasma corticosterone was the proximate mechanism by which condition and dispersal are linked, and tested this by manipulating the level of circulating corticosterone in pregnant females of the common lizard. 3. After parturition, we measured juvenile attractiveness towards the mother and juvenile dispersal of corticosterone (B) and placebo (P) implanted females. 4. Ospring of B females did disperse in lower number than those of P females. B ospring were also more attracted by the mother's odour than P ospring. 5. In quite a few cases, the behavioural response of juveniles was dependent on the interaction between the hormonal treatment and the mother snout±vent length or condition (body weight corrected for snout±vent length). 6. Corticosterone constitutes therefore one of the proximate mechanisms involved in the prenatal control of juvenile dispersal in this species. Along with other results, it is proposed that prenatal control of dispersal has evolved in order to avoid competition between mothers and their ospring.