SANTA CLARITA, Calif.  A private company in Maryland has taken over public libraries in ailing cities in California, Oregon, Tennessee and Texas, growing into the country’s fifth-largest library system.

Now the company, Library Systems & Services, has been hired for the first time to run a system in a relatively healthy city, setting off an intense and often acrimonious debate about the role of outsourcing in a ravaged economy.

A $4 million deal to run the three libraries here is a chance for the company to demonstrate that a dose of private management can be good for communities, whatever their financial situation. But in an era when outsourcing is most often an act of budget desperation  with janitors, police forces and even entire city halls farmed out in one town or another  the contract in Santa Clarita has touched a deep nerve and begun a round of second-guessing.

Can a municipal service like a library hold so central a place that it should be entrusted to a profit-driven contractor only as a last resort  and maybe not even then?