The 2012 pocket edition is 20% thinner and lighter in weight than the 2011 edition due to new production methods, making the 2012 pocket edition handier than ever. We have also increased contrast of the text for greatly improved readability! The 42nd edition is available in a wide array of formats: the pocket edition, somewhat larger spiral bound edition, and larger library edition in print; Apps for iOS and Android devices; and the Web Edition. The digital editions provide us with a platform to update content regularly as developments warrant. The print editions continue to be our annual -snapshot- of the current state of the field of antimicrobial therapy. Highlights of the 42nd edition include the following areas: Resistance to antibacterial agents is increasing at an alarming pace. Materials on management of resistant gram-positive organisms, such as MRSA, and multi-drug resistant gram-negative bacilli, such as E. coli, (Tables 2, 5 and 6 in print) have been extensively updated and expanded. There is increasing clinical application of continuous, or prolonged, infusion of antibacterials for those drugs where optimal efficacy correlates with time above MIC of the target bacteria: cefepime, ceftazidime, doripenem, meropenem, piperacillin-tazobactam. Hepatitis C (HCV) infects over 175 million people worldwide. Two new HCV protease inhibitors, boceprevir and telaprevir, were approved in 2011 for treatment of HCV. Many more drugs are in development in early 2012. Antiretroviral therapy options continue to expand with the approval of new drugs, such as rilpivirine, and new combination formulations of ARV drugs such as Complera. A newly approved macrolide, fidaxomicin, is included for treatment of moderate to severe C. difficille toxin-mediated diarrhea.