The system of payment by results should leave even underperforming providers with capacity for service delivery but then it cannot, by itself, play the central role in terminating some of the contracts. Client characteristics should be documented as accurately as possible to support better client segmentation and better measurement of the relative performance of providers with different caseloads. The allocation of clients to specific providers should be tightly managed by the purchaser so as to minimise, if not eliminate, the scope for providers to “cherry pick” clients with better prospects.