Els Boonacker specialises in corporate law and, in particular, mergers and acquisitions. She advises multinational clients on complex private multi-jurisdictional acquisitions, divestments and joint ventures, as well as public takeovers, and has acted as lead counsel in complex controlled auctions. Her practice also includes advising Dutch public and private companies on shareholders' issues and corporate governance.

In 2007-2008, Els published regularly on contract law in Rechtspraak Contractenrecht. Els is currently seconded to Simpson Thacher & Bartlett LLP and works in their Corporate practice.