The polka mass was first developed and introduced by a Croatian-American priest, Fr. Perk, in the United States in 1973, many years after Pius XII had passed on.
You take the commonly sung parts of mass (Gloria, Agnus Dei, etc) and hymns, and you set them to Polka tunes with accordion music. That’s really the only difference between it and a standard Sunday Mass based on the one time I attended a polka Mass.
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