As health care reform continues to reshape the way medical services are delivered, physicians will find it important to choose carefully the alliances they join and the managed care arrangements in which they participate. Previous columns have discussed the likelihood that health reform will push physicians toward seeking the best alliances and contracts, with promises of volume and semi-exclusivity in exchange for risk assumption and quality assurances by the physicians. Consequently, the huge open physician panels featured in many current managed care arrangements will shrink substantially. The particular relationships and contracts that medical groups forge will often make the difference between thriving and merely surviving in the coming years. Physicians will need to protect their alliances and relationships with extreme care.