Playwrights of any age and from any country can enter the Trinity College London International Playwriting Competition. There are cash prizes of £1000 and the winning plays will be performed at the 2014 International Festival of Playwriting & Performance in London. Additionally, the best plays will be published in a collection that will be distributed internationally.
The categories are plays for performers 11 years and younger and plays for audiences between 12 and 16 years of age. The suggested length is between 20 and 40 minutes, althoug past winners have run to almost an hour.
The entry deadline is December 13, 2013. On the web site there is a pdf called "Some Advice About Playwriting 2013" that you might find useful whether or not you decide to enter the contest. You'll also find the terms and conditions and an entry form here: