<h3>Research Objectives</h3> Quantify the impact and acceptability of outpatient physical and occupational therapy (PT/OT) for breast cancer survivors (BCS) with low-, medium-, or high-severity upper extremity disability (UED). <h3>Design</h3> Retrospective, pre-post observational study. <h3>Setting</h3> Community-based outpatient rehabilitation clinics. <h3>Participants</h3> BCS (identified by ICD-10) who presented for PT/OT and reported UED at baseline via the Quick-Disabilities of the Arm, Shoulder and Hand (QuickDASH) patient reported outcome measure. <h3>Interventions</h3> Standard of care provided by cancer-specialized PT/OT. <h3>Main Outcome Measures</h3> QuickDASH and patient-rated acceptability (1-item): "How likely are you to recommend [this rehabilitation facility] to family/friends", 0 (not likely) – 10 (highly likely)?". <h3>Results</h3> Patients (N=417) were 59.89 ± 12.06 years old and mostly female (99%). They participated in PT (87%) or OT (13%) and attended a median of 10 sessions (IQR: 6.0 – 16.0). At baseline, 62% had high severity UED (QuickDASH >31.5), 25% had moderate severity UED (QuickDASH=18.5-31.5), and 13% had low severity UED (QuickDASH = 13-18.5). From baseline to discharge, significant medium or large effect size (Cohen's d) was observed for each group: high severity UED (M∆=25.13±20.33, d=1.24, p=.00), moderate severity UED (M∆=11.36±11.9, d=0.95, p=.00), and low severity UED (M∆=4.84±9.15, d=0.53, p=.00). Sixty-eight percent of BCS with high severity UED achieved the minimum clinically important difference (MCID), whereas 44% and 4% achieved the MCID in the moderate and low severity UED groups, respectively. Median acceptability across all groups was 10 (n=167, IQR = 10 – 10). <h3>Conclusions</h3> Outpatient cancer PT/OT was associated with significant improvements in patient-reported breast cancer-related UED measured by the QuickDASH, particularly for those with high-severity UED, and was acceptable for all groups. Subsequent studies are warranted to explore UED prevalence and severity by cancer treatment modality, as related to optimizing functional improvement with PT/OT. <h3>Author(s) Disclosures</h3> Drs. Wood, Kendig and Pergolotti receive a salary from ReVital Cancer Rehabilitation, Select Medical.