As a guest conductor, Lacey has conducted at many different opera houses in both the USA and Europe, including Houston Grand Opera, Los Angeles Opera, Santa Fe Opera, Washington National Opera, New York City Opera, Canadian Opera Company, the Liceu in Barcelona, Stockholm Royal Opera, Norwegian National Opera, Greek National Opera, Opera North (Leeds) and l'Opéra Comique in Paris. He has conducted four productions with Graham Vick's Birmingham Opera Company, and has collaborated often with stage director Christopher Alden. He is also active as a symphonic conductor, especially in Germany, Austria, Spain and Italy.