The Apostle's Fast is a period of fasting observed in the Byzantine Catholic Church beginning after All Saints Sunday and ending on the Feast of Saints Peter and Paul (June 29th). It's not as strict as the Great Fast, but still involves abstinence from certain foods. The Archeparchy of Pittsburgh follows the traditional guidelines for fasting during this period.
While not as strict as Great Lent, the Apostle's Fast involves abstaining from meat, meat products, eggs, and dairy products. Fish, wine, and oil are allowed on some days, with specific guidelines varying within the Church.