Dominic Abrams and Melanie Killen published their edition of the Journal of Social Issues drawing together a collection of ten cutting edge papers examining how when and why children engage in or resist excluding one another from social groups. The papers are drawn from all over the world and report evidence about exclusion based on gender, ethnicity, nationality and disability. For more details see:
http://onlinelibrary.wiley.com/doi/10.1111/josi.2014.70.issue-1/issuetoc