Title VII prohibits employers from retaliating against employees who oppose an unlawful employment practice or who participate in an employment discrimination proceeding. This means that if an employee complains about sexual harassment in the workplace, the employer cannot retaliate against that employee by demoting them or subjecting them to some other sort of adverse employment action. It also means that an employer cannot take adverse action against an employee if that employee gives a deposition in a co-employee’s discrimination suit.