Perhaps the most notable development in mental health care over the past 10 years or so has been the creation of early intervention services for psychotic disorders in many countries. The basic premise is that by reducing the time between onset and start of treatment the trajectory of disorders can be modified and outcomes improved. The speed with which this premise has been accepted and early intervention services set up has led some to caution that the evidence on the effectiveness of early intervention is still equivocal and not yet sufficient to warrant such a significant re-configuration of services. The ensuing debate has often been polarised. Here, I will argue that a more nuanced consideration of the pros and cons is needed. The evidence to date does suggest that early intervention can improve both engagement (in itself a notable benefit) and, at least over the short to medium term, social and clinical outcomes. However, if the further development of early intervention services is to be evidence based, notable limitations to existing knowledge need to be acknowledged, in particular concerning the impact of early intervention on longer term outcomes. Finally, the resource implications for rehabilitation and continuing care services of the widespread establishment of early intervention services for psychosis needs more careful study.