St. Francis Xavier Catholic School is open to children of all races and religions. Proirity is given to families who are registered, contributing members of St. Francis Xavier and St. William's Churches. Age requirement for admission is that children must be four (PreK), five (Kindergarten) years old by September 1st of the level year of entry. To enter first grade, children must be six years old by September 1st.

For admission of any new student, an evaluation is held with the principal or level teacher. The following information is required before admittance:

• birth certificate
• baptismal record
• immunization and physical forms
• academic records from previous school(s)
• registration fees paid

Entering students receive a survey test from ITBS; pre-kindergarteners are tested using the KRT from Slosson Educational Publications, and kindergarteners are tested using the Metropolitan Early Childhood Assessment Program.