With the recent introduction of recreational marijuana retail stores throughout the United States and other jurisdictions, research is warranted on whether responsible sales practices are implemented. We assessed store practices/policies in the first two US states to legalize recreational marijuana, Colorado and Washington. We surveyed a random sample of store managers (25 per state) and observed store practices in the largest city in each state (22 in Denver; 24 in Seattle). We analyzed many practices/policies with a focus on underage access (<age 21) to marijuana. Most stores in both states reported that a manager is present at all times and that employee marijuana use on premises is prohibited. All Colorado stores reported they always check age identification compared to 60% in Washington (p < 0.01). All Denver stores we observed checked age identification compared to 83% in Seattle (p < 0.01). All stores in both cities sold a variety of products including candy, concentrates, and vaping devices. We conclude that stores in both states had fairly strict underage access practices but Colorado stores were somewhat stricter. Many products available are likely to be attractive to underage youth such as candy and vaping devices. Our results can help guide jurisdictions in adopting responsible marijuana retail policies/practices.