This study tested the effectiveness of the attachment-based program Video-feedback Intervention to promote Positive Parenting and Sensitive Discipline (VIPP-SD; F. Juffer, M.J. Bakermans-Kranenburg, & M.H. van IJzendoorn, 2008) in decreasing harsh discipline of 43 mothers and their 1- to 4-year-old-children from severely deprived families. Based on previous studies, parenting stress was tested as a potential moderator of intervention effects on harsh discipline. Using a randomized control design, maternal harsh discipline was observed during home visits at the pretest and posttest, and mothers filled in questionnaires at both assessments. The VIPP-SD proved to be effective in decreasing maternal harsh discipline, but only for mothers who experienced higher levels of parenting stress at intake. These findings provide support for the program's ability to improve parenting in families who are most at risk for harsh parenting and for potentially maltreating child-parent interactions. The results are discussed in terms of the VIPP-SD elements most relevant to decreasing harsh discipline, and the challenges of parenting interventions in severely deprived populations.