IMPORTANCE: Shortages in transplantable solid organs remain a critical public health challenge in the United States. During the past 2 decades, all states have implemented policies to increase organ supply, although their effectiveness is unknown. OBJECTIVE: To determine the effects on organ donation and transplantation rates of state policies to provide incentives for volunteer donation. DESIGN, SETTING, AND PARTICIPANTS: Using a quasi-experimental design and difference-in-differences regression analyses, we estimated the effect of policies in all 50 states and the District of Columbia on organ donors per capita and the number of transplantations from January 1, 1988, to December 31, 2010. Analyses were also stratified by type of donor (living vs deceased). Data were derived from the United Network for Organ Sharing. All data collection occurred between July 7 and September 27, 2013. EXPOSURES: Policies of interest were the presence of first-person consent laws, donor registries, dedicated revenue streams for donor recruitment activities, population education programs, paid leave for donation, and tax incentives. Information on states' passage of various policies was obtained from primary legislative and legal sources. MAIN OUTCOMES AND MEASURES: The number of organ donors and transplantations per state, per year, during the study period. RESULTS: From 1988 to 2010, the number of states passing at least 1 donation-related policy increased from 7 (14%) to 50 (100%). First-person consent laws, donor registries, public education, paid leave, and tax incentives had no robust, significant association with either donation rates or number of transplants. The establishment of revenue policies, in which individuals contribute to a protected state fund for donation promotion activities, was associated with a 5.3% increase in the absolute number of transplants (95% CI, 0.57%-10.1%; P = .03). These associations were driven by a 4.9% increase in organ donations (95% CI, 0.97%-8.7%; P = .01) and an 8.0% increase in transplants (95% CI, 3.1%-12.9%; P = .001) from deceased donors as opposed to changes among living donors or transplants from living donors. CONCLUSIONS AND RELEVANCE: Nearly all state-level policies to encourage organ donation have had no observable effect on the rate of organ donation and transplantation in the United States. The one exception was the establishment of revenue policies to promote organ donation, which may have led to small increases in organ donations and transplantations from deceased donors. New policy designs are needed to increase donation rates and curtail the widening gap between organ supply and demand.