After nine years as chairman, Paul Theiss is stepping down from Mayer Brown’s leadership, and Jon Van Gorp, a structured finance partner in New York and Chicago, will take the reins of the 1,685-lawyer firm, the firm announced Tuesday.

The leadership change, effective June 1, comes as Mayer Brown, ranked No. 22 in the Am Law 100, is planning more ambitious growth. In an interview, Van Gorp said he wants to continue building in several markets through lateral hires, talent development and, where possible, combinations.