It used to be the model for reform, with many education and work skills programs so leaving inmates would have a career to enter upon leaving.

I believe it had one of (if the the) lowest recidivism rates in the country. Here's some relevant quotes from an article I found[1], I've heard a few programs about the prison system during that period on the radio:

    Before 1977, all California prisoners had an indeterminate
    sentence. They were given a range of time in which they 
    would be imprisoned, with five years to life being a 
    common sentence. To be freed, inmates had to prove to 
    the parole board that they deserved it, which could mean 
    enrolling in reform-oriented programs, learning a trade, 
    or taking classes. The aim of indeterminate sentencing 
    was to rehabilitate prisoners and, when they were ready 
    to reenter society, free them.
    
    Although the system had its flaws, it also had its 
    successes. According to state statistics, just 15 
    percent of inmates released in 1977 returned to 
    California prisons — an extraordinarily low recidivism 
    rate in comparison to today. Nonetheless, in 1977, then-
    Governor Jerry Brown signed a law that completely 
    overhauled the state's sentencing system, switching the 
    focus from rehabilitation to punishment.

  [1]: http://www.eastbayexpress.com/oakland/how-the-prison-population-exploded/Content?oid=3172693