Thanksgiving season is the time of year when many of us pitch in to help the homeless.

Dr. Jim O’Connell and his team of doctors and nurses will still be helping them next week and the week after that.

You’ve heard of street preachers. O’Connell is a street doctor. He runs the Boston Health Care for the Homeless Program (BHCHP). He and his staff treat men and women not only at shelters and soup kitchens, but also on the streets where they’ve lived in subway tunnels or under highway bridges, sometimes for decades. His staff understands that such chronically homeless men and women, no matter how sick, might never come inside to them.

He calls his “outdoor” patients “rough sleepers,” like the dazed young woman who stopped him in his clinic hall the other afternoon. She was near tears. She said her buddies had gone off and left her. She had no money. She had no blankets or shelter bed for the night and temperatures would get down to freezing. Her $3 cell phone wouldn’t work, though it wasn’t clear whom she might call for help if it did. And she had a raw, painful infection.

“Would you like to see if I can find you a bed inside tonight?” Dr. O’Connell asked her. She looked at him as if he’d just promised her the moon and stars and everything in between.

O’Connell has worked with BHCHP since it began in 1985. He’s just published a book about the patients he’s treated, “Stories from the Shadows: Reflections of a Street Doctor.” He tells intimate, vivid, and often fascinating tales of the anonymous men and women we pass daily on the street.

Take George, a former marine, the 14th of 15 children. He grew up in a Boston housing project and remembers seeing his father die of a brain hemorrhage at home when he was five and his mother die of cancer six years later. He remembers being sent to violent foster homes, running away, and hiding in the basement of a friend for weeks. George says he cannot sleep at night because of nightmares and flashbacks of whippings with a leather belt and broken bones. When he panhandled, he held up a sign that read, “Hit me in the stomach as hard as you can for $1 or in the face for $5.”

Then there’s the 80-year-old man O’Connell treated for heart failure. “One night he proudly announced that he had been the youngest person ever to teach at Columbia University, his alma mater. He graduated at the age of 16, and he was classmates and friends with a slew of American icons,” O’Connell wrote, including Jack Kerouac, Allen Ginsberg, and Lionel Trilling. Then “certain things happened and I was persecuted by those who were jealous of my success,” the elderly man told O’Connell. When he grew convinced of a plot to kill him, he fled New York “and began a 40-year pilgrimage through paranoia and through innumerable towns and shelters across America.”

One of the many things O’Connell says he’s learned in all these years is not to prejudge the men and women he sees — although that’s something most of us do, automatically, within seconds of meeting any new person, never mind someone homeless. “What’s blown me away is how, as you get to know people and their stories slowly emerge, is how complicated their lives are, how they’d been dealt a terrible hand or endured serious mental illness or unspeakable traumas.”

Some of his patients can’t read or write and never made it past the fifth grade. Some had undiagnosed learning disabilities and were labeled troublemakers or slow. Others, like George, wound up in brutal foster care.

O’Connell says he’s also learned about the near-unbearable loneliness of facing death with neither friend nor family by your side. When patients die, they remain in the city morgue until someone claims them. If no one does, they are buried in a pauper’s grave – but not before the BHCHP staff holds a memorial to mark the passing. O’Connell once visited Haiti and “saw poverty like I’ve never seen here. But when you’re taking care of people there, family and kids are all around. They’re never alone. Our folks aren’t just poor, but there’s a poverty of spirit. They’ve lost family and burned bridges. There’s just this cascade of failures and they don’t know how to get back up.”

He remembers one woman facing a serous operation who asked him to take her picture. “She did her nails, fixed her hair, put lipstick on,” he said. She wanted to make sure, if she died, that her daughters would have a picture of their mother looking respectable. She’d not seen them since they were tiny, 25 years before. The woman did die, O’Connell said. But her daughters did not come looking for her.

You hear all this and think Jim O’Connell must be a saint. He quickly disabuses you of that notion.

You may hear all this and think Jim O’Connell, a good Irish Catholic, must be doing this for the Lord. He quickly disabuses you of that notion, too. Although he graduated from Catholic schools and Notre Dame, he fell away from the Church, like many others, because of its treatment of women and gays.

Then came the sex abuse crisis, and that was that.

But he will tell you that BHCHP was founded by a bunch of “radical Catholic” women, nurses and homeless advocates among them, who insisted that the homeless deserve the same dignity and quality of medical care that the non-homeless receive. They wanted real doctors at the clinic, not student doctors or volunteers, but paid physicians who’d be the homeless person’s primary care physician, just like some insured, middle class person has.

You might think, too, that a place like this must be glum and depressing. Actually, no. Not at all.

O’Connell tells you something unsurprising: The men and women here appreciate the care in a way the luckier among us may not.

George, the homeless man mentioned above, once wrote a letter to his fellow patients who were disgruntled about a new BHCHP rule. He talked about how fortunate they were to be off the streets, not getting “robbed, beat up, or murdered.” How “the staff here is beautiful in heart. They can put themselves in our shoes and most don’t care about their paychecks …. They don’t look at us like Homeless Haunts, but as real individuals with needs,” George wrote. “Some homeless people will never get this opportunity. So please let’s all take advantage of this blessing …. Thank you for listening and GOD BLESS all of you.”