Officials estimate that less than 30 percent of the 225,000 pets in Long Beach are actually licensed, though it is legally required of pet owners.
John Kaiser of Long Beach Animal Care Services said that licensing pets is an important step in keeping stray animals off the streets and out of shelters.
"The real plan is if we can get a license or a microchip number, perhaps we can return the animal home before we even impound it," he said.
Many pet owners were more than happy to accept the visitors from animal control.
"I welcome someone coming to my door and asking me for that because it demonstrates that they care," said Clare Curato, a pet owner in Long Beach who was visited Monday.
Long Beach Animal Control has suffered major budget cuts over the last two years. Officials say they could raise millions of dollars if enough pet owners comply with the law and register their pets.
Officers targeted homes where owners might be delinquent in updating their pet licenses or might have acquired new pets. They also checked to make sure that pets were current with vaccinations.
If pet owners are not home, an administrative citation will be issued and a follow-up visit will be made.
A third notice comes with a fine.