Musculoskeletal injuries (MSK-I) are a well-documented problem in military populations and a leading contributor to disability across military services. However, only a portion of Service members who sustain MSK-I report it to medical providers. Although several studies have identified barriers to seeking medical care in military populations, less is known about what motivates Service members to seek care for MSK-I. To describe determinants of medical care-seeking behavior for MSK-I and/or musculoskeletal pain (MSK-P) in recently-enlisted Marines during military training. Qualitative Study. School of Infantry-West (SOI-W), US Marine Corps Base XXX, XXX. 1,097 US Marines entering Infantry Training Battalion or Marine Combat Training at SOI-W. Participants completed written surveys at entry to (baseline) and graduation from SOI-W. Closed-ended question responses were used to calculate MSK-I/MSK-P and care-seeking frequencies. Open-ended responses describing determinants of care-seeking behavior were analyzed using inductive thematic analysis. Ten percent of participants self-reported sustaining MSK-I during basic training, while 14% self-reported sustaining MSK-I in SOI-W training. A greater proportion reported seeking medical care for their MSK-I/MSK-P during basic training compared to SOI-W training. The thematic analysis resulted in three main themes that describe drivers and barriers for seeking medical care: 1) Self-perceived need for medical care; 2) Prioritizing military training; and 3) Training-specific influences. Understanding determinants of care-seeking behavior is valuable when designing intervention strategies to promote early MSK-I treatment. Our findings add to previous research to elucidate reasons underlying the decisions about care-seeking for MSK-I/MSK-P. Interventions, including educational strategies and direct approaches, like embedding medical providers within units, to minimize barriers to seeking medical care in the military may reduce the burden of MSK-I/MSK-P on Service members throughout their military careers.