Thank you for your questions. The U.S. Supreme Court has stated that a quota system cannot be used to achieve compositional diversity. However, an organization can set aspirational goals in order to increase the diversity in which they seek.
There are several policies and practices that can be implemented that can help increase an organization's compositional diversity ( I am assuming compositional diversity (race, gender, age, etc. is what is meant by diversity in this case). Here are a few:
1. Establish a diversity recruiting and marketing campaign where your organization partners with diverse organizations, such as Black or Latino Chamber of Commerce. These relationships can help you explain your brand value to a new market and by highlighting your core values, you may recruit individuals from different groups who share your same core values.
2. A company's best recruiter can be the employees themselves. Establish a campaign through social media where employees highlight your brand value and how your company is a "great place" to work. Encourage them to share their expreriences with their friends on social media. For optimal impact you should have a diversity of employee types participating in this campaign.
Indeed, there are so many more examples of best practices far too many to list here. Please feel free to contact me at firstname.lastname@example.org to discuss further. I would love to hear from you.
Yours in Service,