Mosignor Leonard J. Koster, 84, pastor of St. Charles Church in Arlington form 1947 to 1968, died Saturday at The Little Sisters of the Poor Hospital in Richmond.

during his pastorate, Msgr. Koster was largely responsible for building the present elementary school, church, convent and rectory at St. Charles. Among his othe projects at St. Charles was the opening of a school for retarded children, St. Coletta.

Msgr. Koster was also an ember of the committee that planned the financing and construction of the Bishop Denis J. O'Connell High School in Arlington which opened in 1957.

Msgr. Koster went to St. Charles form St. Rita's Church in Alexandria where he had served as pastor for 23 years and established the Our Lady of Lourdes parish.

He studied at Benedictine College in Richmond and was the first graduate from the school to become a priest. After attending the seminary at Belmont Abbey, N.C., he was ordained in Richmond on June 14, 1919. His first permanent assignment after ordination was at St. Vincent's in Newport News, where he served as assistant pastor for five years before going on to St. Rita's.

Msgr. Koster is survived by a sister, Mary E., of Richmond.