Many standard setting organizations (SSOs) require participants to disclose patents that might be infringed by implementing a proposed standard, and commit to license their "essential" patents on terms that are at least fair, reasonable and non-discriminatory (FRAND). Data from these SSO intellectual property disclosures have been used in academic studies to provide a window into the standard setting process, and in legal proceedings to assess parties' relative contributions to a standard. We develop a simple model of the disclosure process to illustrate the link between SSO rules and patent-holder incentives, and examine some of the model's predictions using a novel dataset constructed from the disclosure archives of thirteen major SSOs. The central message of the paper is that subtle differences in the rules used by different SSOs can influence which patents are disclosed, the terms of licensing commitments, and ultimately long-run citation and litigation rates for the underlying patents.