ABSTRACT We examine firms’ voluntary disclosures of innovation under technology coopetition, focusing on technology standard setting organizations (SSOs). Technology coopetition is characterized by (1) cooperation to determine technology standards, which requires information sharing to reach consensus, and (2) competition for standard implementation to obtain standard-essential patents, which create incentives for firms to deviate from the expected level of information sharing. We document a decrease in 10-K narrative R&D disclosures, more generic 10-K narrative R&D disclosures, and a longer delay of patent disclosures via the USPTO after a firm joins an SSO. Among alternative explanations, our evidence is most supportive of the hypothesis that firms strategically withhold innovation information. JEL Classifications: L15; M41; O32.