Background: As a sequel to a report by the Health Council of the Netherlands on contraception in persons with intellectual disabilities (IDs), a fierce debate about parenthood by such persons occurred, in which a lack of knowledge about parenting competences became clear. Therefore, the Ministry of Health commissioned a study investigating examples of 'successful parenthood' by persons with IDs. Methods: In conformity with the literature and with legal categories, we defined 'successful parenthood' as 'good enough parenthood', meaning no indications for child abuse and/or neglect, no dealings with child protection agencies and no legal custody. We combined a nationwide quantitative questionnaire study with a qualitative interview study. Questionnaires were sent to all institutions involved in caring for persons with ID, interviews were held with 'good enough' parents and their professional caregivers, selected on the basis of returned questionnaires. Results: Parenthood occurs in around 1.5% of persons with ID in the Netherlands and is mostly restricted to those with mild handicaps. In total, 51% of the cases were regarded, by caregivers, as not-good-enough parenthood, 33% were clearly good enough and 16% were doubtful. Predicting factors included the ability and the willingness to follow advice, the quality of the social network and the acceptance of parenting in the community. However, there is not one decisive predicting factor; particularly, the predictive value of the IQ alone is small. Conclusions: A general policy of discouragement of parenthood, asadvocated by the Dutch Ministry, is not supported by our results; moreover, it would probably be impossible and have negative effects on social acceptance of parents with ID. The overall conclusion from the study therefore is that some kind of balancing model, in which positive and negative factors are weighed, may be useful to predict success and need for support. © 2007 Blackwell Publishing Ltd.