This chapter focuses on the infant’s emerging capacity to feel and express affection to other people and the further development of focused attachment relationships. It examines the claims made about the consequences of these attachment relationships for the child’s later emotional development. In humans, a species where child-bearing is associated with considerable risk for maternal death, the ability to form attachments to people other than the biological mother is unquestionably adaptive. Longitudinal analyses suggest that individual differences in displaying affection to parents emerge in the childhood years. Children’s own displays of affectionate behaviour are likely to be a reflection of their own receipt of affection from their parents, with reciprocal levels of affection being observed over time. Jealousy has been defined as ‘a normal response to actual, supposed or threatened loss of affection’. As children form close personal relationships, they may experience jealousy; they may also need to understand the manifestations of jealousy in others.