Caitlin Hyland’s jail cell looks like a regular jail cell. She has family photos, a few books, and a cot. But one thing sets the space apart: the cage on the floor for a 10-week-old puppy!

Four inmates at the Merrimack County jail in Boscawen, New Hampshire, are training puppies for two months. Ms. Hyland has been chosen to raise a chocolate Labrador mix puppy. She must feed the dog three times a day. She walks it every two hours for 20 minutes. She trains it to obey.  The dog stays with her around the clock. Ms. Hyland knows her hard work will soon pay off for someone else. Eventually, the pups being trained at the jail will have a new job: comforting people who have lived through hard things in the military or as first responders. (A first responder is someone trained to help in emergencies. First responders can include police officers, firemen, and paramedics.) Ms. Hyland says training the puppy “feels like a second chance.”

Justin Martin is an inmate at the jail too. He says his dog has given him a sense of purpose. The dog will help someone in the future. But it is also helping him now. He says his puppy is “really changing two lives.” Learning puppy care can teach anyone important life lessons about compassion and responsibility. People in jail have sometimes not learned those lessons yet. The lessons from their four-footed teachers will help inmates in life after their release.

Similar programs exist in jails around the United States. (Inmates at other jails also train dogs that help guide the blind.) And the arrangement isn’t just good for prisoners. It’s good for puppies too. Unlike outside volunteers, inmates can spend all their time with the puppies.

The puppies prance around. They snooze and yelp. Suddenly, jail feels a little more homey.