Over the course of a nearly 30-year friendship, Rebecca Eisner and Lydia Kelley have shared plenty of milestones. The pair were law school roommates and graduated together from the University of Michigan Law School in 1989. They’ve celebrated each other’s weddings and the births of four sons between them. And they cheered one another through a string of career advancements, including making partner at their respective Am Law 100 firms.

On July 1, the two will be celebrating again as Eisner formally takes the reins as partner-in-charge of the 327-lawyer Chicago office of Mayer Brown. The move comes just over a year after Kelley assumed leadership of McDermott Will & Emery’s Chicago office, which is right around the corner in the Loop.