St Bonaventure's Church is open to the public for Catholic worship. Holy Mass is celebrated on Sunday mornings at 8.00am and 10.30am. Services are held throughout the week. The Church serves Lemsford and Welwyn garden City from Stanborough Lakes to Campus West, and the area west of the railway line.

Applications to marry in the church should be made to the Parish Priest. Those who wish to marry there should either live within the parish boundaries, be regular worshippers at the church, or have strong connections with the parish.

There is a choir, a monthly Latin Mass, a Mother and Toddler Group, the Society of St Vincent de Paul (visiting and support), also two groups devoted to overseas aid and development, a monthly Children's Mass, and weekly children's groups for 4 to 12 year olds. The Parish Pastoral Council organise several social functions each year.