Verified answer

Here's three supporting points: Cost, Comfort, Delay of Transition into Adulthood.

Cost: Uniforms can be more expensive for a family who buys from second-hand stores or who relies on hand-me-down clothing from friends and family. Some experts believe the cost is a negative aspect of school uniforms because there is no use for them outside of school.

Comfort: Critics argue that different types of clothing feel comfortable to different people. Some children are more comfortable in a specific material or style of clothing. Uniforms reduce one's ability to choose clothing that fits individual comfort needs. Experts believe that children need to feel comfortable in order to maximize learning, and that uniforms can, in this way, deter academic success for some children.

Delays Transition into Adulthood: Some experts feel that self-expression and self-identification as a teenager helps prepare them to make the leap into adulthood. By forcing teenagers to wear school uniforms, it limits their ability to express in this manner, which may delay their transition into adulthood. One study done in the state of Louisiana found that the only benefits derived from school uniforms ended once the students left middle school, and that no benefits were found for high school students.

This link gives a basic Pro/Cons list for the topic.

http://www.publicschoolreview.com/articles/16

I would add to the cons that some students might not have the money to purchase a uniform.