Donald T. Nicolaisen (1944–2019) was an internationalist, a progressive thinker, and a leader of the U.S. accounting profession. This memorial article traces Nicolaisen's early education and career in the Milwaukee office of Price Waterhouse & Co. in the 1960s, his rise to partner and eventual transfer to the firm's national office in New York City in the 1970s, and his appointment and tenure as the Chief Accountant of the Securities and Exchange Commission in the early 2000s. During his time as the Chief Accountant, Nicolaisen laid the groundwork for the lifting of the reconciliation requirement for foreign private issuers traded on American stock exchanges; the implantation of Sarbanes-Oxley's internal control reporting requirements; and the introduction of XBRL for companies' annual filings with the Commission. Through these initiatives, Nicolaisen leaves behind a legacy of improving both the quality of financial reporting and the efficiency of U.S. capital markets.
JEL Classifications: M41; M42; M48.