In the past, Catholics generally belonged to a parish if they lived within the geographical boundaries of that parish, or if it was a parish which served the ethnic community to which they belonged.
Today, baptized Catholics are still technically members of the parish within whose boundaries they live, unless they take deliberate steps to join a different parish, which many Catholics do.
A variety of factors enter into the decision about which parish to join. The most important thing is that the parish is a community of practicing Catholics in which you are welcome to express and deepen your faith in Jesus Christ. This community should affirm and challenge your spiritual growth while it encourages and prepares you to live out your baptismal commitment.
No parish is perfect, and no parish is an end in itself. The parish is a local manifestation of the Universal Church, the Body of Christ, which spans the boundaries of time and space. Your participation in a parish community should help you experience and express your participation in the Universal Church.
Before you choose a parish, think about what you and your family need in order to understand and practice your Catholic faith. Attend Sunday Mass at different parishes. Read parish bulletins, newsletters or websites to get an idea of what kind of opportunities are available in different parishes. Visit with friends or neighbors, and listen carefully to the reasons they give for why they belong to one parish or another. If you wish, visit with the pastor or other parish staff before joining a parish. After you join a parish, continue to evaluate whether the parish you chose is helping you to become a better member of the Body of Christ.
Keep in mind that, like any other relationship, your connection to a parish is a two-way street. It always depends as much on your own effort and participation as it does on the parish community.

(See also “How Do I Become More Active in the Parish Where I Attend?”)
Related Links:
• How to Choose a Parish.
• What Makes a Good Parish.
• Directory of Catholic Parishes in Waterloo.
• Schedule of Sunday Masses.
• How to Be More Involved in Your Parish.