Messaging about the Affordable Care Act (ACA) has seemingly produced a variety of outcomes: millions of Americans gained access to health insurance, yet much of the US public remains confused about major components of the law, and there remain stark and persistent political divides in support of the law. Our analysis of the volume and content of ACA-related media (including both ads and news) helps explain these phenomena, with three conclusions. First, the information environment around the ACA has been complex and competitive, with messaging originating from diverse sponsors with multiple objectives. Second, partisan cues in news and political ads are abundant, likely contributing to the crystallized politically polarized opinion about the law. Third, partisan discussions of the ACA in political ads have shifted in volume, direction, and tone over the decade, presenting divergent views regarding which party is accountable for the law's successes (or failures). We offer evidence for each of these conclusions from longitudinal analyses of the volume and content of ACA messaging, also referencing studies that have linked these messages to attitudes and behavior. We conclude with implications for health communication, political science, and the future outlook for health reform.