Class actions may be brought against an employer in a number of situations. A class action may be filed for racial, sex, age, or disability discrimination, for instance. Employees can seek compensation through a class action for the employer's failure to pay the employees minimum wage or overtime pay, or the employer's requiring the employees to work "off the clock." Some class actions relate to retirement plans and allege that the employer improperly calculated benefits under the plan, mismanaged the plan, or made unauthorized changes to the plan. Similar class actions can be filed regarding other employee benefit plans.

State workers' compensation laws make it difficult to sue employers for personal injuries suffered by the employees, although sometimes former employees can successfully sue their former employers, such as when the former employees discover that the employer concealed important health and safety information.

Not all employment-related class actions are brought against employers. Some are filed against the companies that supplied hazardous materials to the employees for their work, such as asbestos products or products related to welding.

Class actions are also brought against unions for misconduct such as taking unauthorized payroll deductions, improper political activity, or colluding with the employer to deny the employees their rights.