Adjuvant radiation therapy using accelerated partial breast irradiation (APBI) has been shown to improve local control when delivered during breast conservation therapy to appropriately selected patients. There are a variety of consensus guidelines available to guide patient selection, including ASTRO 2009 and 2016 guidelines, as well as those from the American Society of Breast Surgeons (ASBS), and the American Brachytherapy Society (ABS). Our aim was to analyze patients treated with APBI at our institution to evaluate outcomes and determine the guidelines that identified patients at high risk for failure without restricting ABPI access to appropriate patients. Following institutional review board approval, we conducted a retrospective review of 260 consecutive patients (171 invasive ductal carcinomas, 89 DCIS) treated with APBI at our institution. From January 2006 to December 2010, a balloon device was used (n=86), and from January 2011 to February 2016, patients were treated with a multicatheter device (n=174). A database was created with patient, tumor, and treatment characteristics. Median age at treatment was 64 (range 46 to 89). Median follow-up was 5.98 years (range 0.2 to 11.45 years). The recurrence rate was 4.23% (n=11), with 7 recurrences in the ipsilateral breast, 2 failures in the ipsilateral axillary nodes, and 2 distant failures. The median time to failure was 3.5 years, with a range of 0.75 to 7.1 years. 54.5% of recurrences were in patients with DCIS (n=6), and 83% of those recurred as DCIS (n=5) while n=1 returned as an invasive ductal carcinoma. The overall mastectomy rate was 2.3% (n=6). Eight deaths occurred, and zero were attributed to breast cancer. 96.5% of patients treated are alive without evidence of disease. Twelve patients experienced fat necrosis on mammography, and six patients had biopsies for this reason. Six patients (2.3%) experienced a symptomatic seroma, and four resolved with a single aspiration. By ASTRO 2009 criteria, 39% were suitable, 54% were cautionary, and 7% were unsuitable. 18% of failures (n=2) were suitable per ASTRO 2009 guidelines, while 55% (n=6) were in the cautionary group. By ASTRO 2016 criteria, 67% were suitable, 31% were cautionary, and 2% were unsuitable. 45% (n=5) of patients who experienced recurrence were in the suitable group per ASTRO 2016 guidelines, while 55% were in the cautionary group (n=6). By ASBS 2008 criteria, 98% were suitable, and only one failure was found to be unsuitable by this grouping. By ABS 2013 guidelines, 96% were suitable, including nine patients who experienced recurrence. No suitability group correlated with recurrence or survival. Long-term follow-up of early stage breast cancer patients treated with APBI demonstrated excellent local control. Low rates of salvage mastectomy, fat necrosis, and symptomatic seromas were observed. Classifying patients according to ASTRO 2009 and 2016 suitability groups, as well as those of ASBS and ABS did not correlate with recurrence risk.