This chapter reviews developmental influences on pig behaviour. It begins by discussing prenatal environmental effects on development of pig behaviour, focusing on aspects such as pre-conception and post-conception environments on offspring and piglet behaviour. It also touches on prenatal housing conditions, maternal nutrition, heat stress, infectious diseases and sow management. The chapter moves on to discuss environmental effects during the early postnatal period on the development of behaviour, before concluding with a summary of how swine production systems have gone through various management changes to provide for sow welfare.