The aim is to evaluate the pathological response rate of HPV positive and/or p16 positive low-risk oropharyngeal squamous cell carcinoma (OPSCC) after de-intensified chemoradiotherapy (CRT). Patients will receive 54 to 60 Gy of Intensity Modulated Radiotherapy (IMRT) with concurrent weekly intravenous cisplatin (30 mg/m2). Diagnostic imaging (CT and/or MRI) will be obtained 4 to 8 weeks after completion of CRT to assess response. All patients will have surgical resection of any clinically apparent residual primary tumor or biopsy of the primary site if there is no evidence of residual tumor and will undergo a limited neck dissection to encompass at least those nodal level(s) that were positive pre-treatment, 4 to 14 weeks after CRT. The primary endpoint of this study is the rate of pathological complete response (pCR) after CRT. Longitudinal assessments of quality of life and patient reported outcomes will be obtained prior to, during, and after CRT.