Background: Australia's public access residential early parenting services provide programs to assist parents who self-refer, to care for their infants and young children. Treatment programs target infant feeding and sleeping difficulties and maternal mental health. There is limited systematic evidence of maternal and infant mental health, psychosocial circumstances or presenting problems, or the effectiveness of the programs. The aim of this study was to contribute to the evidence base about residential early parenting services. Methods: A prospective cohort design was used. A consecutive sample of mothers with infants under one year old recruited during admission to a public access residential early parenting service for a 4 or 5 night stay in Melbourne, Australia was recruited. They completed structured self-report questionnaires, incorporating standardised measures of infant behaviour and maternal mood, during admission and at one and six months after discharge. Changes in infant behaviour and maternal psychological functioning after discharge were observed. Results: 79 women completed the first questionnaire during admission, and 58 provided complete data. Women admitted to the residential program have poor physical and mental health, limited family support, and infants with substantial behaviour difficulties. One month after discharge significant improvements in infant behaviour and maternal psychological functioning were observed (mean (SD) daily crying and fussing during admission = 101.02 (100.8) minutes reduced to 37.7 (55.2) at one month post discharge, p < 0.001; mean (SD) Edinburgh Postnatal Depression Scale at admission = 11.3 (5.7) reduced to 6.78 (4.44), at one month, p < 0.001) which were sustained at six months. Participant satisfaction with the program was high; 58 (88%) found the support of the nurses and 50 (75%) the social support of other mothers very helpful. Conclusions: This psycho-educational approach is an effective and acceptable early intervention for parenting difficulties and maternal mood disturbance, and contributes to a system of comprehensive mental health care for mothers of infants.