<h3>Purpose/Objective(s)</h3> We completed a phase III trial comparing standard of care (SOC) adjuvant radiotherapy (60 Gy, ± Cisplatin) with de-escalated adjuvant chemoradiotherapy (DART) (30-36 Gy, Docetaxel) following margin clearing surgery. We hypothesized that DART would result in improved speech and swallowing metrics that would be durable over time. <h3>Materials/Methods</h3> MC1675 eligibility and inclusion criteria have been previously reported. Functional oral intake scale (FOIS), performance status scales (PSS), penetration/aspiration (Pen/Asp), and modified barium swallow impairment profile (MBSIMP) were assessed and recorded prospectively pre-operatively, pre-SOC/DART, 1-month, and 12-months post-SOC/DART. Descriptive statistics (frequencies, mean, median, standard deviation) were computed, and t-tests were used to compare results at each time point as well as paired t-tests to compare 1- and 12-month results to baseline. <h3>Results</h3> 194 patients (mean 59.4 yrs, SD 8.48; 89.2% male) met criteria (SOC: 64; DART: 130; randomization 1:2). Most had pT1/2 (87.7%), pN1 (84.5%), tonsil primary (60.8%) disease, with no difference in age, sex, primary subsite, or stage between groups (p>0.05). 25 patients underwent pre-operative swallow evaluations (SOC: 13, DART: 12). There were no differences in MBSIMP, FOIS, Pen/Asp Scores, or PSS (p>0.2). 189 patients underwent the Pre-SOC/DART swallowing evaluation, with a significant difference in epiglottic movement (p=0.0241) on MBSIMP, favoring the SOC arm. At 1-month post-SOC/DART, differences on MBSIMP in oral residue (p=0.0011), onset of pharyngeal swallow (p=0.0057), and oral swallow score (p=0.0054), PSS normalcy of diet (p<0.0001) and PSS public eating (p=0.0005) were superior for DART. There was no difference in FOIS (p=0.0673), Pen/Asp (p=0.1939) or PSS understandability of speech scores (p=0.3086). Investigating changes from Pre-SOC/DART to 1-month Post-SOC/DART demonstrated improvement on MBSIMP in oral residue (p=0.0041), epiglottic movement (p=0.0184), oral swallow score (p=0.0194), and FOIS (p=.0186), all favoring DART. The pharyngeal swallow score approached significance in favor of DART (p=0.0652) and there was no difference noted in Pen/Asp (p=0.1053). At 12-months Post-SOC/DART, DART was superior on MBSIMP in oral residue (p=0.0149) and oral swallow score (p=0.0317), with no difference in FOIS (p=0.3216) or Pen/Asp (p=0.7970). The change from Pre-SOC/DART to 12-months Post-SOC/DART demonstrated a significant benefit on MBSIMP in oral residue (p<0.0001) and pharyngeal swallow (p=0.0198) favoring DART. <h3>Conclusion</h3> Patients undergoing margin clearing surgery and neck dissection treated with adjuvant de-escalated chemoradiation therapy demonstrated improved objective swallowing outcomes throughout treatment, with persistence at 1 year. This was most notable for the oral phase of swallowing.