The tumor biology of small renal masses represents a spectrum that includes extremes such as benign histologies and potentially aggressive renal cell carcinoma, with many indolent tumors occupying the space in between. A wide variety of treatment options is now available, ranging from active surveillance to surgical excision. Renal mass sampling has great potential to provide improved risk stratification in the future, particularly when combined with molecular profiling. Treatment should be individualized based on tumor biology, renal functional considerations, the efficacy and potential morbidity of each treatment modality, and patient comorbidities and preferences. While partial nephrectomy remains the standard of care in appropriate patients, an emerging and important role for thermal ablation has been established in the treatment of small renal masses. Further studies evaluating thermal ablation will be needed to define the optimal indications and true oncological efficacy of this modality.