When Patti Smith was 20 years old, she packed up and left her New Jersey hometown for the Big Apple, leaving behind her family and a string of miserable factory jobs. When she arrived in New York, she met the boy who would first become her lover, and then her lifelong friend: photographer Robert Mapplethorpe.

Smith is a bona fide rock legend, renowned as much for her progressive politics and tireless activism as for her contributions to music. But her new memoir is not intended as a "history of punk rock," as Smith herself told me in our interview. Sure, it's full of anecdotes about living in the Chelsea Hotel in the 1970s, of meeting Allen Ginsberg and Jimi Hendrix—but at its heart, it's an account of the friendship that grew between two young artists who were just beginning to find their way in the world. The black-and-white photographs that punctuate Just Kids are almost unbearably poignant: The two wide-eyed kids will go on to redefine their respective art forms. Somewhere along the way, they'll get old. Worse: In 1989, Mapplethorpe will die of AIDS. Twenty years later, Just Kids is Smith's incredibly moving tribute to her lost friend.

PATTI SMITH: So... where are you calling from?

MERCURY: Portland, Oregon.

I like Portland. I'm trying to think when I was there last.

I remember seeing you in LA a few years ago, and you'd just come from Portland, and you talked about how you ate a really good burrito in a parking lot that you bought out of a truck.

[Laughs] That sounds like me. Let's see, I know I performed during the Taste [of Oregon] festival, but I was also there for the HP Lovecraft Festival. That's a pretty cool thing to have, the world's only HP Lovecraft Festival.

We also have the world's only velvet painting museum.

That has to be really great.

Yeah, it's pretty cool.

I'm sure it's cool. In the end almost everything's cool, if you step back... you can laugh about velvet painting and all, but some of it is unbelievable. So ambitious! And somebody did that. Some human being.

Well, your publicist told me very sternly that I could only have 20 minutes, so I guess we should talk about your book. I found it really moving. It made me cry.

Oh, I'm... well, I'm not sorry, because I cried writing it. I guess the tears are within it.

It must've been very difficult to write.

Sometimes it was, yes.

Could you explain what the title of your book meant to you, and why you chose to title the book after that particular anecdote?

It was just one of those things that happened. [Robert Mapplethorpe and I] went to Washington Square, and it was a beautiful pre-fall, Indian summer day, and we were both dressed as cool as we knew how to dress, and to have these people, especially this woman, staring at us and saying, "I think they're artists! Maybe they're famous...." Robert was beaming, and then the husband says, "Oh, they're just kids." And then we just laughed, because it was like the woman had been taking us up, and was making us feel really cool, and then the husband waves us off. And in the end they were both right. We were young artists, and we were just kids.

It's kinda shocking to look at some of the pictures and realize how young you actually were.

Well, exactly, and thank you for saying that, because that's one of the reasons I wrote the book—because a lot of people write about both of us or us together with some kind of perception that has nothing to do with reality. I mean I have read, even in major biographies, such fabrications about us, at such a young age, doing or saying things that we were just too unformed and too shy and too self-conscious and unsophisticated to have [done]. I really felt that a lot of writers have robbed us of our childhood and our youth—and I really wanted to give that back, to infuse what I know is the truth into all of these other perceptions of either one of us.

I can imagine your book would be particularly inspiring to read as a 19- or 20-year-old artist.

Well I was hoping that, especially for young people who are confused about what they want to be, who they are, what their sexuality is—or feeling they're not getting anywhere. To remind them that what's beautiful about our youth is that we are beautiful. It's when we have beauty, and we have a lot of bravado, but we're also unformed—unless someone is a real prodigy—and it takes time. It takes time to evolve and it takes time for our work to evolve. And so I'm hoping that just as when I did Horses, I did Horses, for people who felt like they were outsiders, to give them a voice and to remind them they weren't alone, and I'm hoping that the book will have that effect.

The book is so detailed, down to what you were wearing on any given day. How'd you remember all that?

I had a lot of diaries, letters, pictures, and journals. I had those teenaged-style journals my mom would get me for my birthday, and because my birthday's right near New Year's Eve, I would always start a new one [every year]. Sometimes I wouldn't finish them, but I would try to every day write something. It might be something like "Cut Robert's hair like a rockabilly star." "Bought green tights." "The moon is full." "Met Janis Joplin." So I have in my diaries, it's like a touchstone. And then my journals had longer recollections, and I had a lot of letters from Robert. Sometimes it was just old photographs; I could see what we were wearing. I still have some stuff. I didn't rely on memory—my memory is pretty good, but I had almost a daily account. In reading all these old diaries and reading these journals, I could really sit and read and remember.

Do you still write every day?

Yeah, I'm always writing. I'm always noting things down. Just like in my children's baby book—when they took their first step, their first drawing, when they first said "rainbow"—I tried to write those things down so they would have touchstones.

How long did it take you to write the book?

A long time. Robert asked me if I would write our story right before he died, and I promised him I would, but it took me a long time. I started taking notes for it, but then with the loss of my husband, and then my brother, it was such a blow—to suddenly be a widow, my husband was only 44, I had two children.... My life just changed so drastically, it took me a long time to get my feet on the ground and regroup and be able to just sit and write, especially about loss. After losing so many people I couldn't face writing about Robert. I promised it in '89 and finished it in 2009, so 20 years went by. But I finally did it. I mean I wasn't working continuously for 20 years—I'd take it out, start it again, put it away, take it out, start it again. But I didn't want to put the book out unless I felt that it resonated... that it had the truth of our relationship.

The book focuses almost exclusively on that relationship, rather than on your own development as a musician.

Well, that isn't the book I promised Robert. I wasn't writing an autobiography. That's why Robert and I are on the cover—it's about us. I'm hoping that people see the cover and see the title and understand that this isn't a book that explains the history of punk rock or something, it's not that book. I'm not saying that would be a bad book to write, it's just that the book I promised Robert was about [us]. The development of my music veers off to a whole other world. I incorporated into this book something of the music, because it did include Robert, but I wanted to keep our story... that's what I was writing about. The end of the book was hard to write because when I started writing the book my husband was still alive, and so was my brother—when I started writing the notes to it, I never dreamed that I would have lost my husband. So it was difficult.

You wrote very little about your husband, but it was an affecting line. [Of her late husband Fred "Sonic" Smith, she wrote: "Of the man who was to become my husband, I wish only to say that he was a king among men and men knew him."]

Well, my husband was a very private man. I've done a lot of poems and songs for my husband, but if I ever wrote something for him I would do it in my own private way. By saying very little, I was hoping people would get some sense of my love for him.

Can you talk about the book's visual elements—did you select the photographs and drawings that are included?

I did everything with the book. I helped design the book, the cover, the flaps, I chose the font... I was lucky to have a very good designer, and she was interested in the same things I was, and we went through just about every page—how it would look, how the type would fall on each page... I worked as hard on the mechanics of the book as anything. The weight of the paper, how the photographs would be presented. Every aspect of the book was important to me

It took me awhile, looking at the cover photo of you two, to notice that Robert is wearing a mesh shirt.

[Laughs] Which was later made into art... it's hanging in a museum somewhere, that very mesh shirt.

That picture was taken on our [second] anniversary, on September 1, 1969. And I thought it was the perfect cover because we were so happy that day. We weren't as naĂŻve as we were when we first met, but it was a happy day. We had everything ahead of us. And also, I thought it was funny because where I come from, these big sandwiches are called "hogies." In New York they're called "heroes." When I looked at the picture and realized it said "heroes," I thought, "Wow, that's so amazing, how beautiful is that." And then someone else looked at it and said, "It's really funny how you have this sandwich in the background." So it's really just New York slang for a big sandwich.

One theme you return to over and over in the book is that of the artist's social responsibility. How do you, as a longtime artist and activist, stay invested in social change?

Sometimes in small ways, sometimes in large ones. Sometimes it's through prayer, you pray for the people in Haiti now, for them to have the strength to endure what they're dealing with; then we'll do a fundraiser, next week, to raise money. Sometimes a song against Guantanamo Bay, or the treatment of John Walker Lindh. Sometimes it's prayer, sometimes it's money, sometimes it's marching. Each day one tries to be a citizen, sometimes in a small way. I'm not out on the streets every day, I can't say that I'm an activist first, because I'm an artist, and that's where I put the lion's share of my attention, but every day I try to be aware of things.

New York City is basically a character in the book, but it's changed considerably since you arrived.

It's the same in the manner that it's built on a grid, you can walk anywhere, it has cafés open... but it has changed in the last 20 years or so. It's gotten expensive, upwardly mobile, it's lost its welcoming hand to poorer people and to young people who have little money, or to artists and dreamers. I think that's more than sad, I think it's heartbreaking and wrong. And a lot of our historic buildings are being leveled to build more condominiums—we've all lost our practice spaces, our art studios, myself included, my band all had to move out of the city because it became too expensive, the young people can't find apartments. And it can't be exaggerated, it's all true. I can't find an affordable place to work on paintings, or practice with my band, and it shouldn't be like that. So in that way it's changed quite a bit. In other ways, like I said, I can walk anywhere, take the subway, and it's a very safe city. It's always been safe, though.

I noticed that in the book—you never seemed to feel unsafe.

Well you just didn't go down deep in the East Village, or down Avenue C, where there were a lot of drug dealers and a lot of crime, you sorta stayed out of certain areas. But also, I wasn't afraid, and I think sometimes fear makes us victims. I never was afraid anywhere in New York. I was hungry, but I wasn't afraid.