This research compared two forms of psychodynamic psychotherapeutic interventions for 67 clinically referred infants and their mothers. One was an infant-led psychotherapy delivered through a program called Watch, Wait, and Wonder (WWW). The other was a mother–infant psychotherapy (PPT). Infants ranged in age from 10 to 30 months at the outset of treatment, which took place in weekly sessions over approximately 5 months. A broad range of measures of attachment, qualities of the mother–infant relationship, maternal perception of parenting stress, parenting competence and satisfaction, depression, and infant cognition and emotion regulation were used. The WWW group showed a greater shift toward a more organized or secure attachment relationship and a greater improvement in cognitive development and emotion regulation than infants in the PPT group. Moreover, mothers in the WWW group reported a larger increase in parenting satisfaction and competence and decrease in depression compared to mothers receiving PPT. Both WWW and PPT were successful in reducing infant -presenting problems, decreasing parenting stress, and reducing maternal intrusiveness and mother–infant conflict. Some potential reasons for the differential treatment effects and the theoretical, clinical, and methodological implications from the findings are discussed. ©1999 Michigan Association for Infant Mental Health.