Answer

Refer to Happy Are Those Who Are Called to His Supper: On Preparing to Receive Christ Worthily in the Eucharist, a document from the USCCB’s Committee on Doctrine: "We should also come to the sacred liturgy appropriately dressed. As Christians we should dress in a modest manner, wearing clothes that reflect our reverence for God and that manifest our respect for the dignity of the liturgy and for one another" (available at www.usccb.org).