These days, many employees work part time, some by choice and some because it's the only work available. Statistics show that women are more likely than men to work part time. These part-time employees are protected from sex discrimination in wages, just like full-time employees.
Employees are protected from discrimination in pay by two laws: Title VII of the Civil Rights Act of 1964 and the Equal Pay Act. Title VII prohibits sex discrimination in wages among similarly situated employees. The Equal Pay Act requires employers to pay men and women equally for doing equal work.
Under Title VII, it's illegal to discriminate in wages based on sex and other protected traits (such as race or color). This means, for example, an employer couldn't simply pay women a lower starting salary than men in the same position, or use benchmarking analyses to raise men's salaries while leaving women's salaries lower than national standards.
Title VII protects part-time employees as well as full-time employees. However, to win a Title VII lawsuit, an employee must show that she was paid lower wages because of her sex -- and not for any other reason. For example, if an employee can show that male employees are hired at higher starting salaries based on their prior earnings, while female employees are not, that might be grounds for a sex discrimination claim. However, if an employer recently lowered its starting salaries because of the economic downturn, and all of the most recent hires happen to be female, that might not demonstrate sex discrimination.
The Equal Pay Act (EPA) also prohibits sex-based wage discrimination, and it also applies to part-time employees. Under the EPA, men and women are entitled to equal pay for equal work. However, the jobs being compared must be quite similar. And, differences in pay that are based on anything other than sex are legal. For example, if an employer routinely paid full-time employees at a higher hourly rate than part-time employees (perhaps because it preferred for employees to work full time), that wouldn't violate the EPA, even if most of the part-time employees are female.
Title VII and the EPA also prohibit sex-based discrimination in benefits. This includes both insurance benefits (such as health care coverage and disability) and job perquisites, like a company car, relocation bonus, and vacation days. However, both laws prohibit only discrimination based on sex. An employer is free to offer full-time employees a better benefits package than part-time employees -- and many employers do just that. Often, only full-time employees are entitled to health coverage, for example.
If, however, an employer offered male part-time employees better benefits than women who work part time, that would be illegal discrimination.
If you believe you are being discriminated against in wages because of your sex, you should talk to an experienced employment lawyer right away. A lawyer can assess your situation and help you figure out the best way to protect your rights.