Jaclyn Marie Allen and Evan C. Nielsen were married April 16 at St. Mark's Episcopal Church in Islip. The reception was at Chateau La Mer in Lindenhurst. She is an academic adviser for Stony Brook University and is the daughter of Jean Marie and James Allen of Islip Terrace. The bridegroom is a New York City police officer and is the son of Laurie and Arthur Nielsen of Smithtown. The bride earned a bachelor's degree from St. John's College. The groom earned an associate degree from Suffolk County Community College. They live in Islip Terrace.