Breast-conserving therapy consisting of segmental mastectomy followed by whole-breast irradiation (WBI) has become widely accepted as an alternative to mastectomy as a treatment for women with early-stage breast cancer. Accelerated partial-breast irradiation (APBI) is a shorter, alternative radiation technique for select patients with favorable early-stage breast cancer. We review here the different modalities of APBI delivery and discuss the possible benefits and harms associated with these treatments.