 He has acted as Legal Consultant of the Export Processing Zone Authority (1985–86), and a Member of the following organizations—the Philippine Bar Association, the Integrated Bar of the Philippines, the Philippine Institute of Certified Public Accountants, the Philippine Canine Club, Inc., United Way, Philippines, Harvard Alumni Association; President, Rotary Club of Makati Ayala.He is an Honorary Member in the Association of Fellow and Legal Scholars of the Center for International Legal Studies, and a Member of the Mimosa Golf and Country Club, Fontana Resorts, Capitol Hills Golf Club, and the Tower Club.Villanueva was editor-in-chief of the Ateneo Law Journal from 1980 to 1981.