In St. Patrick's Cathedral at one o'clock last Saturday Afternoon, Deirdre Elizabeth Cooke, daughgther of Mr. and Mrs. Robert Francis Cooke of Allenhurst, N.J. and New York, was married to Donald Joseph Schroeder, son of Mrs. Felt Schroeder of Bloomfield, N.J. Msgr. George Murphy, pastor of Holy Trinity Church, N.Y., officiated at their marriage as he had for the bridge's parents and for her twin sister. Concelebrants of the Nuptial Mass were Father Stephen Findlay, OB, former Headmaster of Delbarton School, Father Timothy Brennan, Ob, Delbarton School, Morristown and Father Joseph Miele, pastor of St. Anslem's, Wayside, N.J. The reception was held in the Waldorf Astoria -- as it was for her parents and sister.

The bride wore her mother's wedding dress of heavy ivory satin with a portrait neckline encircled by an exquisite bertha collar of antique French lace. The voluminous skirt had deep inserts of matching lace and flowed into a cathedral train. Framing her face was a mantilla of alencon lace made for Mrs. N. Louis Paladeau for her wedding 25 years ago.

Eileen Cooke Brown, the bride's twin was matron of honor, and Sister Suzanne Marie Cooke of the Religious Order of the Sacred Heart, also sister of the bride, the maid of honor. The bridesmaids were: Jane Hurley, Mary MacLellen, Mary Rogers, Pamela Brown, Deborah Hart, and Amy Wry. Kelley Ann Day was flower girl and John Day the page boy.

The bridegroom was served by Thomas R. Dougherty and Edward F. DePalma. His groomsmen were Charles Contessa, Gregory and Christopher Cooke, brothers of the bride and her brother-in-law, J. McCauley Brown; Christopher Carey, Joseph Corderi, Robert Gilmore, Nicholas P. Gacos, and Jack Waldron.

The bride, whose father is an investment manager, is an alumna of Marymount Secondary School, Tarrytown, N.Y., Marymount College of Virginia, and Katharine Gibbs in New York. She made her debut in December 1975 at a dinner dance given for her and her twin Eileen, by their parents at the Deal Golf and Country Club, Deal, N.J. She was also a member of the St. Vincent Debutante Dances in Westchester, N.Y. and the Gothams in New York City. She is a granddaughter of the late Mr. and Mrs. Thomas R. Brown Jr. of New York City. Mr. Brown was an executive of the U.S. State and Treasury Departments and recipient of the Intelligence Medal of Honor. Her paternal grandparents are the late Mr. and Mrs. Edward F. Cooke of Richmond Hill, N.Y. Mr. Cooke Sr. was an investment manager.

Mr. Schroeder, an alumnus of Delbarton School and Boston College (Mass.), is studying for his master's degree at Seton Hall University (N.J.)

After their return from Aspen, Col., the couple will live in Princeton, N.J. where Mr. Schroeder is a financial analyst with the Radio Corporation of America.