This article describes a think-aloud study conducted to identify factors that influence the decisions made by digital reference "triagers" when performing triage on questions received by digital reference services. This study follows and expands on a Delphi study that identified factors that triagers agreed on after the fact of their performance of triage by identifying factors that triagers take into consideration during their performance of question triage. Thirty-eight factors that influence triage decisions were identified, in eight categories. Eight of these factors are intrinsic to the question itself; the remaining thirty factors are extrinsic to the question, situating it in a context for the user and the service. These factors must be taken into consideration by any future system for automated triage.