In collaboration with Consulting Editor Dr. Helen Boucher, Drs. Aruna Subramanian and Dora Yuk-Wai Ho have created an extremely timely and relevant issue for infectious disease physcians, as the field of biologics is exploding. These new agents are being used in rheumatologic diseases, hematologic malignancies, solid tumors, and other conditions; there is a lack of guidance in the literature on how to address their infectious risks.  The first 9 articles explain the mechanisms of action of the biologic agents and the infectious disease risks associated with their immune system targets.  The last few articles go into more depth on the viral, fungal, and mycobacterial infections that are potentiated by biologics, and discuss recommended prophylaxis and preventative strategies, including vaccinations. Specifically, articles are devoted to the following: TNF inhibitors; Agents targeting B cells; Agents targeting T cell activation; Direct T cell inhibition and agents targeting T cell migration and chemotaxis; IL-1 and IL-6 and other interleukin and IgE inhibition; Check-point inhibitors; Tyrosine kinase inhibitors for heme malignancies; EGFR inhibitors and other Tyrosine kinase inhibitors for solid tumors; Targeting JAK-STAT signaling and complement pathway for inflammatory diseases; Viral infections Potentiated by Biologics (and Prophylaxis); Endemic Fungal Infections Potentiated by Biologics (and prophylaxis); Mycobacterial Infections Potentiated by Biologics; and Vaccinations for patients on biologics. Readers will come away with the clinical overviews of these topics to improve prevention and management of patients treated with biologics.