This issue of JAMA includes 4 articles from JAMA Contributing Writers that provide insights about several key topics in medicine and health policy. John P. A. Ioannidis, MD, DSc, and colleagues (Vinay Prasad, MD, and Adam Cifu, MD) point out that change occurs in medicine continually, reflecting new evidence, and a certain amount of reversal of established medical practices is inevitable, but the rate of abandonment of ineffective practices is slow.1 Ezekiel J. Emanuel, MD, PhD, discusses the need to control the growth in US health care expenditures and identifies commonly targeted areas that represent false cost controls and highlights other major areas that may achieve real cost savings.2 Robert H. Brook, MD, ScD, discusses the new era in US health care being ushered in with implementation of the Affordable Care Act, and delineates key metrics to measure and monitor to determine both anticipated and unanticipated effects of the new law on the health of the US population.3 Elliott S. Fisher, MD, MPH, and colleagues (Jonathan Skinner, PhD, and James Weinstein, DO, MS) suggest a “withhold” approach to slowing the growth in Medicare spending that may achieve savings while allowing motivated clinicians and health care organizations to recover the proposed financial cuts and thus maintain or even increase their reimbursement.4