Contrary to a popular perception, under federal law, employers do not have to provide breaks to hourly employees. Instead, employers need only pay for all short "coffee" breaks, those that typically last about 10 or 15 minutes. If they are offered, "lunch" breaks or breaks for other meals need not be paid.
However, California law affords broader protections for employees than does the federal law. Under California's rules, an employer must offer one unpaid lunch break for every five hours an employee works. The break has to last for 30 minutes, and the employer must be sure that the break indeed involves the employee's being excused from work in order to eat lunch. A "working lunch" is only permitted in certain circumstances, and the employer must be willing to pay for that lunch.
Moreover, an employer must ensure that its hourly workers get a 10-minute break for every four or so hours the employee works. This break has to be compensated, and it also has to be offered when an employee works even a substantial part of a four-hour period, so an employee who puts in six hours in a day is entitled to two paid breaks and one unpaid lunch period.
Not giving employees their breaks carries potentially severe consequences, as an employer has to pay an additional hour of wages to the employee if he or she has to give up his or her break. If the employer refuses to do so, the employer may be sued for a wage and hour violation. Moreover, if an employer actually fires an employee for trying to take a break to which he or she is legally entitled, then the employee may be able to sue for wrongful termination.