A dress code states what students must not wear, while a uniform code states what students will wear.
Dress codes are believed to reduce conflict, gang violence and theft among students. Disallowing baggy clothing (which can hide weapons) and gang-related colors as well as certain expensive shoes and jewelry is often a dress code principle.
Opinions and research are divided on this issue, but one principle of dress codes is the thought that students who aren't distracted by fear, sexual references or drug and alcohol references will be more focused on academics.
In areas with students coming from varied socioeconomic backgrounds, dress codes can "even the playing field." Students who can't afford the expensive clothing worn by peers may feel better when some of those types of clothing are banned for all.
Many T-shirts contain references to alcohol, drugs, tobacco or profanity; none are issues teens should promote at school. Often a school will ban all T-shirts with writing to eliminate the need to judge shirts one by one.
Clothing designed to entice the opposite sex may disrupt the learning environment. Teens who dress seductively may aggravate the already-present sexual thoughts in high school students.