The objectives of this Campbell systematic review are as follows: a) To establish whether group‐based parenting programmes are effective in improving the emotional and behavioural adjustment of children less than three years of age; b) To assess the role of parenting programmes in the primary prevention of emotional and behavioural problems. The findings of this review provide some support for the use of group‐based parenting programmes to improve the emotional and behavioural adjustment of children under the age of 3 years. There is, however, insufficient evidence to reach any firm conclusions regarding the role that such programmes might play in the primary prevention of such problems. Furthermore, there are limited data available concerning the long‐term effectiveness of these programmes, and the results from the two studies for which data were available produced borderline insignificant findings. Further research is required. Synopsis Parenting practices play a significant role in the development of emotional and behavioural problems in children, and parenting programmes which are aimed at the parents of infants and toddlers thereby have the potential to prevent the occurrence of such problems. The findings of this review provide some support for the use of group‐based parenting programmes to improve the emotional and behavioural adjustment of children under the age of 3 years. The limited evidence available concerning the extent to which these results are maintained over time, however, is equivocal, and it may be that during this period of rapid change in the infant's development, further input at a later date is required. More research is needed before questions of this nature can be answered. Abstract BackgroundEmotional and behavioural problems in children are common. Research suggests that parenting has an important role to play in helping children to become adjusted, and that the first few months and years of a child's life are especially important in establishing patterns of emotional, cognitive and social functioning which will in turn influence the child's future development and in particular, their mental health. Parenting programmes may therefore have a role to play in improving the emotional and behavioural adjustment of infants and toddlers. ObjectivesThe objectives of this review are as follows: a) To establish whether group‐based parenting programmes are effective in improving the emotional and behavioural adjustment of children less than three years of age b) To assess the role of parenting programmes in the primary prevention of emotional and behavioural problems. Search strategyA range of biomedical and social science databases were searched including MEDLINE, EMBASE, CINAHL, PsychLIT, Sociofile, Social Science Citation Index, ASSIA, the Cochrane Library including SPECTR, CENTRAL, National Research Register (NRR) and ERIC. Selection criteriaOnly randomised controlled trials of group based parenting programmes were included, and studies that had used at least one standardised instrument t...