Sculptor Richard Serra, "street artists" Margaret Kilgallen and Barry McGee, photographer Sally Mann and installation artist Pepon Osorio. Serra, seen installing one of his massive steel-plate structures in the atrium of an office building, needs a big place for his works. McGee and Kilgallen make gallery art but prefer grafitti. Mann, known for nude photos of her children, is now doing landscapes. And, says Osorio: "I need to create a space. That is overpowering."

Ann Hamilton, who works with textiles; impish multimedia artist John Feodorov; miniaturist Shahzia Sikander; and James Turrell, whose medium is light itself. Linking them: spirituality, "a thread that connects us all," says host S. Epatha Merkerson. "I think ambiguity is where the spiritual lies," says Feodorov, who combines Navajo and Christian themes provocatively. Turrell explains how he designs his projects "to bring the cosmos closer."

Bruce Nauman, Maya Lin, Louise Bourgeois and Kerry James Marshall, "four contemporary artists who deal in notions of identity," says Steve Martin, who introduces the hour. Marshall uses black themes in his paintings and installations; 90-year-old Bourgeois, a sculptor, frequently fashions hands; Lin, known for the Vietnam War Memorial, is seen at work in Grand Rapids, Mich. And Nauman makes psychologically infused videos and installations, including an outdoor stairway.

Mel Chin, Matthew Barney, Michael Ray Charles and Andrea Zittel, artists "who raise questions about the things we consume every day," says tennis great John McEnroe, who introduces the hour. Marshall explores racial stereotypes; filmmaker Barney approaches themes of sex and conflict elliptically; Zittel lives in---or wears---her utilitarian "installations"; and Chin's art has found its way into everything from a burned-out Detroit house to TV's "Melrose Place."

Stories (in one form or another) is the theme linking the four artists profiled in Part 1 of four: Kara Walker, Kiki Smith, Do-Ho Suh and Trenton Doyle Hancock. Walker explores her African-American heritage in silhouettes that are at once genteel and macabre. Smith, a sculptor, often deals with death. “We were like the Addams family,” she says of her childhood. So-Ho Suh, a native of Korea, is concerned with space, individual and collective. One project is a “house” he made of transportable fabric. “I want to carry my home with me all the time---just like a snail,” he says. And painter Trenton Doyle Hancock looks to combine “comic-book narratives with the history of abstraction” in his mythical creatures. Filmmaker John Waters introduces the film.

Part 2 (of four) connects photographer Collier Schorr, and multimedia artists Gabriel Orozco and Janine Antoni with the theme of loss and desire. Schorr describes her pictures of high-school wrestlers and the teenage boys in a German family (who pose dressed as soldiers). The objects Orozco has worked with include ping-pong tables and a Citroen, while Antoni works with such things as soap, chocolate and her own body. Jane Alexander introduces the film.

Part 3 (of four): Time is the theme grouping the four artists profiled here. Among them: Martin Puryear, who's known for his large installations; Paul Pfeiffer, whose installations and video projects play off pop culture and sports; Vija Celmins, who specializes in natural forms; and Tim Hawkinson, whose installations have been as big as a football field. Choreographer Merce Cunningham hosts.

Conclusion. Humor is the theme grouping the four artists profiled here. Among them: Eleanor Antin, who finds room for a wink or two in her social commentary; Raymond Pettibon, whose comic-book art is for adults only; Elizabeth Murray, whose paintings are vibrant and zany; and Walton Ford, whose watercolors unite the natural and political worlds. Comedian Margaret Cho hosts.

Power and its victims is the theme of this episode, which profiles artists Cai Guo-Qiang, Laylah Ali, Krzysztof Wodiczko and Ida Applebroog. Guo-Qiang, whose materials include gunpowder, talks of “the aesthetic of pain”; Ali, whose round-headed figures appear cartoonish (but are quite serious) is seen working with choreographer Dean Moss; Wodiczko's video projections honor victims of violence; and Applebroog explores “how power works” in paintings, drawings and sculptures.

Memory is the theme as artists Susan Rothenberg, Mike Kelley, Hiroshi Sugimoto and Josiah McElheny are profiled. McElheny, a glassblower, often puts his own spin on works of the past. Kelley looks for “materialist ritual” in his video art, paintings and sculptures. Sugimoto calls his photographs “fossilizations of the time.” And Rothenberg, a Southwestern painter, says “I don't want to get too literal. I want the viewer to do the work, too.” Isabella Rossellini is the host.

“Structure” is the theme as artists Matthew Ritchie, Fred Wilson, Richard Tuttle and Roni Horn are profiled. “Modern art is a gift,” says Ritchie, whose room-sized installations are rooted in line drawing. Wilson's installations are formed by “putting things together,” not making them. Tuttle, a veteran painter-sculptor, likes to explore “the part which I can't see,” as does Horn, a sculptor-photographer. “The unknown,” she says, “is where I want to be.” Introduced by Sam Waterston.

“Play” is the theme as artists Jessica Stockholder, Ellen Gallagher, Arturo Herrera and Oliver Herring are profiled. Stockholder's sharp-colored works frequently incorporate plastic objects, and Gallagher's paintings and films offer “a way of constantly looking for home.” Herrera makes collages and wall paintings from drawings and abstract photos. And Herring's work ranges from somber knitted sculptures to fanciful video works and photographic “statues” of people. The NBA's Grant Hill hosts.

The fourth season begins with romance as the theme grouping the artists profiled here, including photographer Laurie Simmons, media artist Pierre Huyghe, and painters Judy Pfaff and Lari Pittman.

“Protest” is the theme. Profiled: painter Nancy Spero, photographer An-My Le, media artist Alfredo Jaar and conceptual artist Jenny Holzer.

Ecology is the theme. Profiled: photographer Robert Adams, and sculptors Mark Dion, Ursula von Rydingsvard and Iñigo Manglano-Ovalle.

Paradox is the theme. Profiled: painter Robert Ryman, filmmakers Mark Bradford and Catherine Sullivan, and media artists Jennifer Allora and Guillermo Calzadilla.

The Season 5 premiere highlights artists who seek to reconcile past with present, expose injustice and celebrate tolerance in their works, including South African native William Kentridge, who creates poetic allegories on stage and film. Also: visual artist Carrie Mae Weems, who reflected on how the 1960s influenced the 2008 presidential election in a photo-video series, and Doris Salcedo of Colombia, who honors her country's marginalized peoples through sculptures and installations.

Artists who mine the world of fantasy are featured, including Jeff Koons, who explores notions of taste and pleasure; abstract artist Mary Heilmann; German-born landscape photographer Florian Maier-Aichen, who spices photographs with computer-enhanced imagery; and Chinese artist Cao Fei, who explores perception.

Artists who observe and satirize society are featured, including Yinka Shonibare, who's shown creating a piece about the 2008 economic meltdown; Cindy Sherman, who creates photographic series and films in which she portrays various characters; and Paul McCarthy, who pokes fun at cultural icons ranging from Disney characters to Queen Elizabeth II.

Artists who tackle projects that are complex and/or vast in scope are featured, including Ethiopian-American painter Julie Mehretu, who's shown creating a large work about the history of market-based capitalism; John Baldessari, who mixes photomontage, painting and language in his pieces; Korean-born Kimsooja, whose art combines techniques of video, performance and installation; and Allan McCollum, who creates large quantities of almost identical objects.

The Season 6 premiere focuses on Chinese contemporary artist Ai Weiwei, Ghanian sculptor El Anatsui and American photographer Catherine Opie, whose works often share thematic similarities, including a focus on transformation.

Examining the works of sculptor David Altmejd, Japanese animation artist Tabaimo and avante-garde sculptor Lynda Benglis, which explore the shape-shifting potential of the human figure through taboo subjects and the innovative use of media.

Glenn Ligon, Mary Reid Kelley and Marina Abramovic, whose works examine historic events and often challenge assumptions about them, are profiled.

The Season 6 finale focuses on oil painter Rackstraw Downes, minimalist painter Robert Mangold and sculptor Sarah Sze. Their works explore the space that lies between art and existence, the seeing and the knowing.

The Season 7 premiere features Thomas Hirschhorn, who creates an installation with help from public-housing residents; photographer Graciela Iturbide, who focuses on Mexico; and Leonardo Drew, who continually experiments with materials and processes.