Performance Guidelines for Using Modernizr

As Paul Irish said, best practice of including modernizr to your site vary. It depends what are you testing for and how large your page is. Generally, if you are testing for JS API, it is better to stick it to the end of the document. If you are using styling hooks, loading in the <head> seems like better approach, because we will avoid FOUC (flash of unstyled content) and content yanking.