Multisource and 360-degree feedback are emerging methods in the medical education assessment literature. Nursing feedback in particular has been identified as a point of emphasis regarding what medical education leadership would most value for incorporating into their evaluations. There is no currently accepted tool for multisource feedback in the emergency department (ED). To answer this call, we conducted a qualitative study to elucidate nurse perspectives on evaluation of emergency medicine residents. We conducted individual semistructured interviews of ED nurses with experience working alongside residents via volunteer recruitment. Transcripts were coded independently by each author and then reviewed collaboratively to resolve differences. Codes were created by inductive thematic analysis and subsequently underwent constant comparison and classical content analysis. Recruitment continued until analysis of transcripts showed thematic saturation. We organized the interview transcript into chunks of information, arranging 407 quotes from the 10 interview transcripts into 17 codes and six themes regarding observable resident behaviors. Representative quotes and exemplar cases added detailed description to the meaning of these codes. The identified themes for observable resident behaviors included "general communication style," "medical knowledge," "efficiency," "patient communication," "nurse communication," and "professionalism." An additional 13 codes addressed the themes of barriers and catalysts for feedback. The identified themes on observable resident behaviors aligned well with prior literature and with the Accreditation Council for Graduate Medical Education (ACGME) Milestones. The interviews also highlighted nurse perspectives on barriers and catalysts for feedback that would be useful to incorporate into the design of an assessment tool.