Some economics of mental health 'carve-outs'.

We discuss the rationale for benefit carve-out contracts in general and for mental health and substance abuse in particular. We focus on the control of adverse selection as a principal explanation and find that this is consistent with the wide-spread use of sole-source contracting with periodic rebidding. We also find that some degree of risk sharing is common; we interpret this as a method of balancing cost-containment incentives with incentives to maintain access and quality on unmeasured dimensions.