This study updates the prevalence rates of single chronic conditions and multiple chronic conditions (MCC) among US adults using data from the 2012 National Health Interview Survey (NHIS). The research found that approximately half (117 million) of US adults have at least one of the 10 chronic conditions examined, and 1 in 4 adults (25.5%) have MCC. The prevalence of MCC remained stable between 2010 (26.0%) and 2012 (25.5%), despite a previous trend of increasing prevalence. The study highlights the need for ongoing surveillance and research to address the public health concern of MCC, including improving healthcare and public health systems, enhancing self-care management, and providing better tools for healthcare providers. The NHIS estimates are conservative as they only capture 10 out of 20 chronic conditions and do not include mental health conditions or long-term care settings.This study updates the prevalence rates of single chronic conditions and multiple chronic conditions (MCC) among US adults using data from the 2012 National Health Interview Survey (NHIS). The research found that approximately half (117 million) of US adults have at least one of the 10 chronic conditions examined, and 1 in 4 adults (25.5%) have MCC. The prevalence of MCC remained stable between 2010 (26.0%) and 2012 (25.5%), despite a previous trend of increasing prevalence. The study highlights the need for ongoing surveillance and research to address the public health concern of MCC, including improving healthcare and public health systems, enhancing self-care management, and providing better tools for healthcare providers. The NHIS estimates are conservative as they only capture 10 out of 20 chronic conditions and do not include mental health conditions or long-term care settings.