Contemporary

In the United States, a movement toward using uniforms in state schools began when Bill Clinton addressed it in the 1996 State of the Union, saying: "If it means that teenagers will stop killing each other over designer jackets, then our public schools should be able to require their students to wear uniforms." As of 1998 approximately 25% of all U.S. public elementary, middle and junior high schools had adopted a uniform policy or were considering a policy, and two thirds were implemented between 1995 and 1997.

There are an abundance of theories and empirical studies looking at school uniforms, making statements about their effectiveness. These theories and studies elaborate on the benefits and also the shortcomings of uniform policies. The issue of nature vs. nurture comes into play, as uniforms affect the perceptions of masculinity and femininity, complicate the issue of gender classification and also subdue the sexuality of girls. With uniforms also comes a variety of controversies, pros, cons and major legal implications.

There are two main empirical findings that are most often cited in the political rhetoric surrounding the uniform debate. One of these, the case study of the Long Beach Unified School District, is most often cited in support of school uniforms and their effectiveness whereas Effects of Student Uniforms on Attendance, Behavior Problems, Substance Use, and Academic Achievement is the most frequently cited research in opposition to the implementation of school uniform policies.

Effects of uniforms on students
The case study of the Long Beach Unified School District was the study of the first large, urban school in the United States to implement a uniform policy. In 1994, mandatory school uniforms were implemented for the districts elementary and middle schools as a strategy to address the students' behaviour issues. The district simultaneously implemented a longitudinal study to research the effects of the uniforms on student behavior. The study attributed favourable student behavioral changes and a significant drop in school discipline issues to the mandatory uniform policy. This case study attributed the following noticeable outcomes to the use of uniforms throughout the district:

Fewer absences and truancies;
Fewer referrals to the office for behavior problems;
Fewer suspensions and expulsions;
Reduced by 28% (elementary) and 36% (middle school);
Decreased crime and vandalism;
Reduced by 74% (elementary) and 18% (middle school);
Better grades, and in some cases, significantly higher achievement.

Other research found that uniforms were not an effective deterrent to decrease truancy, did not decrease behavior problems, decrease substance use, or increase student achievement.

A study suggested that "instead of directly affecting specific outcomes, uniforms act as a catalyst for change and provide a highly visible opportunity for additional programs" within schools. In fact, Brunsma et al., 1998 considered that this was the case with the Long Beach Unified School District case study as several additional reform efforts were implemented simultaneously with the mandatory uniform policy.

Brunsma stated that despite the inconclusiveness of the effects of uniforms, they became more common because "this is an issue of children's rights, of social control, and one related to increasing racial, class and gender inequalities in our schools."