Notice and comment provisions in agency rulemaking provide an important mechanism for the public to contribute to policy. Yet there is limited research on how interest groups participate in this process. California's passage of an ergonomics standard in 1997, the only current state statute in the country, provides a useful, high salience policy case for examining public commentary. Between an initially proposed comprehensive standard and the enactment of a much weaker regulation occurred the largest public response in California's state Occupational Safety and Health Administration history. Through a detailed content analysis of the notice and comment submissions we identify features of participation and claimsmaking that differ between business and nonbusiness submissions. Business groups were the large majority of participants and also presented a disproportionate amount of evidence, using an "abstract-technical" policy frame to assert the illegitimacy of the ergonomics standard. Labor, public health organizations and private citizens represented less than one-third of the participants and relied primarily on experiential information and a "concretized-moral" characterization of policy issues in support of the standard. The existence of these distinct "interpretive communities" that mobilize different resources raises questions about whether public commentary can fulfill its purported "democratic accountability" purpose as well as underline the limitations of appealing to scientific expertise for solving complex policy problems