The Affordable Care Act requires health insurers to justify rate increases of 10 percent or more for nongrandfathered plans in the individual and small-group markets. Analyzing these filings for rates taking effect from mid-2012 through mid-2013, insurers attributed the great bulk—three-quarters or more—of these larger rate increases to routine factors such as trends in medical costs. Insurers attributed only a very small portion of these medical cost trends to factors related to the Affordable Care Act. The ACA-related factor mentioned most often, but only in a third of the rate filings in this study, was the requirement to cover women’s preventive and contraceptive services without patient cost-sharing. But, the insurers who point to this requirement or other ACA-related costs attributed only about 1 percentage point of their rate increases to the health reform law.