Exploring Sentiment, Values, and Misinformation Surrounding Vaccination Legislation on Twitter: A Case Study of California’s Passage of SB277

California remains among a handful of U.S. states with no clause for a personal belief exemption for required vaccines due to passage of SB277. As vaccines represent an important tool in the public health arsenal against SARS-CoV-2 and may yet be required by schools and employers, other states may consider enacting laws similar to SB277 to address COVID-19 and future outbreaks of infectious diseases. In this case study of California's SB277 bill, we examine the sentiment, values, and misinformation shared on Twitter regarding this bill in the days leading up to, during, and after its successful enactment into law in 2015 using a sample of geocoded tweets (<i>N</i> = 1,000). Results of our content analysis of tweet sentiments before and after the law was signed offer evidence for significant differences in vaccine misinformation [<i>χ</i>^<i>2</i>(1, <i>N</i> = 1,000) = 4.01, <i>p</i> = .045, <i>Φ</i> = .06], and individual values related to power [<i>χ</i>^<i>2</i>(1, <i>N</i> = 1,000) = 71.57, <i>p</i> < .001, <i>Φ</i> = -.27] and achievement [<i>χ</i>^<i>2</i>(1, <i>N</i> = 1,000) = 4.39, <i>p</i> = .036, <i>Φ</i> = .07]. Findings suggest that although most tweets did not contain misinformation, few provided scientific evidence to back claims. Implication for theory, research, and health policy and practice are discussed.