Abstract Aim: The aim of the study was to evaluate the effects of process-oriented training in supportive breastfeeding counseling for midwives and postnatal nurses on the time lapse between the initial breastfeeding session, introduction of breastmilk substitutes and solids, and the duration of breastfeeding. Materials and Methods: Ten municipalities in Sweden were randomized to either the intervention or control groups. The intervention included a process-oriented training program for midwives and postnatal nurses in the intervention municipalities. Primiparas (n=540) living in either an intervention or control municipality were asked to participate in a longitudinal study to evaluate the care given. Data collection for control group A (CGA) (n=162) started before the intervention was initiated. Data for control group B (CGB) (n=172) were collected simultaneously with the intervention group (IG) (n=206). The mothers responded to questionnaires at 3 days, 3 months, and 9 months postpartum. Results: As a result of the process-oriented training program for midwives and postnatal nurses, the IG mothers had a significantly longer duration of exclusive breastfeeding, even if the initial breastfeeding session did not occur within 2 hours after birth, than the corresponding group of CGA mothers (p=0.01). Fewer infants in the IG received breastmilk substitutes (in the first week of life) without medical reasons compared with the control groups (p=0.01). The IG infants were significantly older (3.8 months) when breastmilk substitutes were introduced (after discharge from the hospital) compared with the infants in the control groups (CGA, 2.3 months, p=0.01; CGB, 2.5 months, p=0.03). Conclusion: A process-oriented training program for midwives and postnatal nurses was associated with a reduced number of infants being given breastmilk substitutes during the 1st week without medical reasons and delayed the introduction of breastmilk substitutes after discharge from the hospital.