While absolute pitch (AP)—the ability to name musical pitches without reference—is rare in expert musicians (Levitin & Rogers, 2005; Ward, 1999), anecdotal evidence suggests that some musicians may better identify pitches played on their primary instrument than pitches played on other instruments. We call this phenomenon “instrument-specific absolute pitch” (ISAP) and offer the first theory of underlying mechanisms (Reymore & Hansen, 2020). This theory is situated in neuroscientific research on the multimodal nature of expertise (e.g., Krishnan et al., 2018; Proverbio & Orlandi, 2016). We propose that informative timbral cues arise from performer- or instrument-specific idiosyncrasies or from timbre-facilitated tonotopic representations and that sounds of one’s primary instrument may activate kinaesthetic memory and motor imagery, aiding pitch identification (Hansen & Reymore, 2021). Hypotheses derived from this theory are tested in two professional oboists. Only one of the two oboists showed an advantage for identifying oboe tones over piano tones. For this oboist, pitch-naming accuracy decreased and variance around the correct pitch value increased as an effect of transposition and motor interference, but not of instrument or performer. These results suggest that some musicians possess instrument-specific absolute pitch while others do not and that candidate mechanisms behind this ability capitalize on timbral cues and motor imagery. In a Registered Report (Hansen & Reymore, 2021), we plan to extend these findings to a larger population of oboists. A deeper understanding of instrument-specific absolute pitch has theoretical implications for research on musical expertise, absolute pitch, timbre and pitch cognition, and musical embodiment, as well as practical implications for musical practice and pedagogy. Finally, the theory offers several directions for future research, employing behavioral, neuroimaging, and brain stimulation methods.