Chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL) are essentially different manifestations of the same disease that are similarly managed. A number of molecular and cytogenetic variables with prognostic implications have been identified. Undetectable minimal residual disease at the end of treatment with chemoimmunotherapy or venetoclax-based combination regimens is an independent predictor of improved survival among patients with previously untreated or relapsed/refractory CLL/SLL. The selection of treatment is based on the disease stage, presence or absence of del(17p) or TP53 mutation, immunoglobulin heavy chain variable region mutation status, patient age, performance status, comorbid conditions, and the agent's toxicity profile. This manuscript discusses the recommendations outlined in the NCCN Guidelines for the diagnosis and management of patients with CLL/SLL.