It's under control at the moment," says Susan Bay Nimoy of the passion for art collecting that she shares with her husband, actor Leonard Nimoy.

"Not really," he counters, with a smile. "We’re still at it aggressively."

"We’re almost at the end of buying large pieces, though, because we now have limited space," Susan clarifies. "We’re focused on collecting really important works on paper—glorious works on paper like those by Roy Lichtenstein, Robert Gober, Brice Marden and Gordon Matta-Clark. We are also buying watershed works, like the black plank by John McCracken. We like it when an artist explores new materials or new ideas."

For the Nimoys, that sense of discovery has never grown old. Art collecting was a revelation for these Los Angeles residents, who find it difficult to contain their exuberance when talking about their collection. Since neither grew up in art-centric families, they never thought much about art residing in homes rather than in museums. That changed when they became members of Los Angeles’ Museum of Contemporary Art (MOCA) and started visiting collectors’ homes. "We saw this gorgeous art and realized how exciting it could be to live with it," Susan says. "That was the catalyst to our collecting."

The large and still-growing assemblage—they have never counted the pieces—is split between their Manhattan and Los Angeles residences. Their Los Angeles house, its interior design by Rosemary Peck, combines the airy sophistication of an upscale art gallery with the comfort of a Zen retreat. Art pops out everywhere—sometimes literally. Visitors are greeted at the front door by their recent acquisition, "Ovals Template" (2006), a plasma-cut steel-plate sculpture by Rita McBride. In the living room a conceptual art piece, Isa Genzken’s "Kindershirm" (2004), made of plastic, wood, metal, palm leaf and fabric, seems to float on its pedestal. "This is a very layered work. You have to walk around it," says Susan. "To me it’s all about childhood and the relationship to the culture. It’s very complex and endlessly interesting."

Leonard is a busy photographer who has exhibited widely and published a book of his images and thus has placed collecting on the back burner. "His emphasis was on realizing his own vision," Susan explains. "My focus was on learning about the world of contemporary art. And we did that together by joining MOCA when I became a trustee. I was on a learning curve and brought Leonard along."

Their collection has evolved through the years from outsider art, which they equate with "getting their feet wet," to pieces that fell somewhere in between modern and contemporary art. "Now after 20 years, we’re more drawn to minimalism and conceptualism," says Susan.

Leonard originally came to art through his work as an actor and director. "I did a project in the 1970s called ‘Vincent,’ a one-man show about Vincent van Gogh," he says. "I wrote and staged it and portrayed Theo van Gogh, Vincent’s brother. Because of that project, I did extensive research on him and looked at his work wherever I could."

Leonard’s acting career was an impetus to collecting in another way. When he and Susan met in 1987, he was represented by the Phil Gersh Agency. Phil and Bea Gersh were important contemporary art collectors who had given a large portion of their collection to MOCA in 1989, and the couple opened up the world of contemporary art to the Nimoys.

"For the first couple of years, anytime we saw a piece we would call the Gershes and they would drop everything and come over and see what we had because they were such excited collectors themselves," Leonard remembers. "For a while we wouldn’t buy anything they didn’t approve. Gradually we began to do things on our own, and then things evolved."