How does the presence or absence of a child's mother affect the child's behavior during mildly stressful medical procedures such as injections? Two studies were carried out, the first with 18-month-old children and the second with 5-year-olds. In each study, 1O children were randomly assigned to a condition with mother present and 10 to a condition with mother absent when the child received routine immunization as part of a regular visit to a pediatrician's office. Many 18-month-olds in the mother-absent condition protested upon the mother's departure. However, when the children received their injections, it was those in the mother-present condition whose behavior was rated as significantly more negative than those in the mother-absent group. The 5-year-olds' behavior during and after the injection was also rated as significantly more negative for the children in the mother-present condition. Objective coding of these children's behaviors showed that the ones with mother present cried longer when they received the injections and continued to fuss more while being dressed and taken from the examining room. The findings were interpreted to mean that, given a minor pain experience, children may inhibit protest if the mother is absent.