Kim Kardashian┬áhasn’t slowed down her efforts when it comes to prison reform … as evidenced by her latest visit to a prison in California and the inmates she came face-to-face with during her trip.

A source with direct knowledge tells TMZ … Kim spent a day at Pelican Bay State Prison in Crescent, CA earlier this week. We’re told her focus was to meet with inmates in solitary confinement, speaking with them in depth about the toll the lockup can have on their mental stability.