ST. LOUIS, June 27, 2017 /PRNewswire/ -- Express Scripts Holding Company (Nasdaq: ESRX) today announced the election of Kathleen M. Mazzarella to the company's Board of Directors effective June 27, 2017."We are honored that Kathy will be joining our Board, and we appreciate the wealth of expertise and experience she will bring to us," said George Paz, Chairman of the Board. Ms. Mazzarella has served as Chairman, President and Chief Executive Officer of Graybar Electric Company, Inc., a distributor of electrical, communications and data networking products and provider of related supply chain management and logistics services, since June 2012, and previously served as Executive Vice President and Chief Operating Officer from December 2010 to June 2012. Ms. Mazzarella joined Graybar in January 1980, and has held increasing roles of seniority, including Senior Vice President, Sales and Marketing and Senior Vice President, Human Resources and Strategic Planning. Ms. Mazzarella was elected a Director of Graybar in January 2004, and has served as Chairman since January 2013. Ms. Mazzarella has served as a director of Waste Management, Inc., since October 2015, and as a director of the Federal Reserve Bank of St. Louis since January 2015, serving as Chairman since April 2016. Ms. Mazzarella also serves on several other boards, including the St. Louis Regional Chamber, United Way of Greater St. Louis, the Saint Louis Club, the Webster University Business and Technology Advisory Board, and the Westminster College Board of Trustees. She is a member of The Business Council, Vistage Worldwide, Inc., the International Women's Forum, The Committee of 200, and Civic Progress. About Express Scripts Express Scripts puts medicine within reach of tens of millions of people by aligning with plan sponsors, taking bold action and delivering patient-centered care to make better health more affordable and accessible.