To effectively meet clinician information needs at the point of care, we must understand how their needs are dependent on both context and clinician type. The Infobutton Manager (IM), accessed through a clinical information system, anticipates the clinician's questions and provides links to pertinent electronic resources. We conducted an observational usefulness case study of medical residents (MDs), nurse practitioners (NPs), registered nurses (RNs), and a physician assistant (PA), using the IM in a laboratory setting. Generic question types and success rates for each clinician's information needs were characterized. Question type frequency differed by clinician type. All clinician types asked for institution-specific protocols. The MDs asked about unfamiliar domains, RNs asked about physician order rationales, and NPs asked questions similar to both MDs and RNs. Observational data suggest that IM success rates may be improved by tailoring anticipated questions to clinician type. Clinicians reported that a more visible Infobutton may increase use.