Melancon, the longest serving head of the AICPA, joined in 1995 also as the youngest individual hired for that position. He is also the CEO of the Association of International Certified Professional Accountants, taking that title with the combination of the Chartered Institute of Management Accountants and AICPA in 2017.

Events during his tenure include his spearheading the CPA Vision Project, the launch of CPA.com, the computerization of the CPA exam, creation of the National Commission for Diversity and Inclusion, the Centers for Audit Quality and the Dynamic Audit Solution.

In 2012, the AICPA entered a joint venture with the Chartered Institute of Management Accountants with the organizations launching the Chartered Global Management Accountant designation