Twitter Inc. chief executive officer Dick Costolo is stepping down July 1.

Cofounder and chairman Jack Dorsey will serve as interim ceo as the company looks for a permanent replacement.

Costolo will stay on Twitter’s board, while Dorsey will continue as ceo of Square Inc., the digital payments firm he cofounded in 2009.

Dorsey said, “The future belongs to Twitter thanks in large part to Dick Costolo’s dedication and vision. Dick has put a world-class team in place and created a great foundation from which Twitter can continue to change the world and grow. We have an exciting lineup of products and initiatives coming to market, and I look forward to continuing to execute our strategy while helping facilitate a smooth transition as the board conducts its search.”