The aims of this study was to investigate how personality develops over time and at which time points behaviours and therefore personality stabilises in red junglefowl. Personality seems to have three developmental stages; weaning, sexual maturity and the period in between. The finding that some of the behaviours in this study stay correlated despite these periods of developmental changes would suggest that these behaviours are strongly linked to underlying mechanisms such as physiological traits. Personality in red junglefowl seems most stable in adulthood after sexual maturity, when several behaviours became correlated between ages. Therefore future studies should try to integrate variation in underlying mechanisms of behaviour such as hormonal profiles and heritability, to investigate their role and links in stabilising behavioural responses and therefore personality across an individual’s life.