This is a multicenter, single-arm pilot study incorporating brentuximab vedotin and dose attenuated rituximab, cyclophosphamide, doxorubicin, and prednisone (R-CHP) into initial therapy for elderly patients with DLBCL. Vincristine will be omitted from the standard R-CHOP regimen given the overlapping toxicities with brentuximab vedotin. CD30 positivity will be determined at enrollment and patients will be enrolled into a CD30 positive and negative group in equal numbers. Additionally, a Comprehensive Geriatric Assessment (CGA) will be performed on all patients, but this will not be used to guide treatment decisions.