borrowed shamelessly from: All Saints of America Orthodox Mission DeQueen, Arkansas
Most people who are invited to a formal gathering (weddings, etc.) will wear appropriate clothing for the occasion. Considering that we stand in the presence of the All Mighty God and His angelic hosts during Church services, it is only appropriate that we should dress in the best that we have. We must be careful not to bring our casual ways into the Church for they engender a casual attitude toward God our Creator. This is the reason we do not sit during most of the services or cross our legs when we do sit down. This casual attitude can lead to inattention and therefore disrespect.
Men and boys should wear clean appropriate pants, shirts, and shoes with socks. Sloppy clothing, logo T-shirts, athletic shoes are great for play but not for the Divine services.
Women and girls should wear modest dresses or skirts that cover the knees and blouses that cover the upper arms. Women and girls are required to cover their heads during prayer as the Apostle Paul instructs in his epistle to the Corinthians. Makeup such as lipstick and lip balm should be removed prior to reverencing icons or approaching for Holy Communion.
Exceptions are made for the younger children but as they grow older they should be instructed in the proper dress for these practices set patterns for future habits.