Anxiously attached 12-month-olds and their mothers as assessed in the Strange Situation were randomly assigned to an intervention and a control group to test the hypothesis that infant-parent psychotherapy can improve quality of attachment and social-emotional functioning. Securely attached dyads comprised a second control group. Intervention lasted 1 year and ended when the child was 24 months. ANOVAs were used to compare the research groups at outcome. Intervention group toddlers were significantly lower than anxious controls in avoidance, resistance, and anger. They were significantly higher than anxious controls in partnership with mother. Intervention mothers had higher scores than anxious controls in empathy and interactiveness with their children. There were no differences on the outcome measures between the intervention and the secure control groups. The groups did not differ in maternal child-rearing attitudes. Within the intervention group, level of therapeutic process was positively correlated with adaptive scores in child and mother outcome measures.