Point-of-care information needs are common and frequently unmet. One solution to this problem is the use of Infobuttons, which are context-sensitive links from electronic health records (EHR) to knowledge resources, sometimes involving an intermediate broker known as an Infobutton Manager. Health Level Seven (HL7) has developed the Context-Aware Knowledge Retrieval (Infobutton) standard to standardize the integration between EHR systems and knowledge resources. While the standard specifies a set of context attributes and standard terminologies, it leaves to knowledge resources the flexibility to decide how to use these attributes and terminologies to retrieve the most relevant content. This paper describes some of the challenges faced by knowledge resources in trying to locate the most relevant content based on the attribute values for a given Infobutton request. Various approaches to content retrieval are discussed, including the role of indexing with standardized codes, the role of text-based search engines together with their ranking algorithms, and the role of hybrid approaches. Knowledge resource developers must carefully consider business rules, heuristics, and precision/recall tradeoffs when implementing the HL7 Infobutton standard.