To date, the impact of the evo-devo “revolution” has been almost entirely restricted to the morphological domain—discussions of the role of contingency and development in the evolution of morphological traits being commonplace. In contrast, very little attention has been paid to contingency and development in the evolution of behavioural traits. This observation leads one to ask if there is any in-principle reason why this is the case. In this chapter, I respond to this question by motivating the application of the conceptual toolkit from evo-devo to the behavioural domain. I argue that there is evidence from inheritance of behaviour through social learning that demonstrates that development plays an important causal role in the evolution of behavioural traits. Furthermore, this evidence is as strong as, if not stronger than, analogous evidence used to motivate the evo-devo approach in the morphological domain. On these grounds, we should be just as willing to engage in the evo-devo research program when considering the evolution of behavioural traits as we are when considering the evolution of morphological traits.