This article says, "If you are reading this article, your kid probably doesn’t need preschool."

http://www.slate.com/articles/double_x/the_kids/2013/01/how_important_is_preschool_if_you_are_researching_early_education_philosophies.html

A quote that sums it up: "Research suggests that preschool only benefits children from these disadvantaged families (in particular, families that are below the poverty line, whose mothers are uneducated, or who are racial minorities). This could be because preschool acts as a kind of “equalizer,” ensuring that for at least a few hours a day, these kids get the same high-quality interaction with adults as more advantaged children do, which helps to even the developmental playing field."

Thoughts?