The main photo is of Zac Efron which may be use to portray a teenager in their prime with fashionable clothes or as some call it these days 'swagger'.
In addition the slogan used (who says you' re only young once?) may be illustrated to signify what the film is about and images used such as the suit and briefcase on the floor represent the hatred for adult life and the love for teenage life.
Kidulthood
The setting the poster seems to look like a very urban area which contributes to how the teens look. in addition the clour are very dark which may infer that the area they live in is bad. Evidence odf this may be the baseball bat seen being held by one of the teens .
the slogan (before adulthood comes kidulthood) is very short and catchy and may relate to every day life .


