Before choosing a job, what is the main way you research a company's approach to workplace diversity?
I look for policies and official statements on their website.
I look to see what role diversity plays in the company structure (i.e., if there's a specialized Office of Diversity or minority networking groups, etc.)
I look at their history of participation in cultural or diversity-related events (i.e., minority-targeted career fairs).
I ask my interviewer(s) about the company stance on diversity.
I do not research a company's diversity policy.