In “The Serial Portrait: Photography and Identity in the Last One Hundred Years,” the National Gallery of Art showcases 153 works by 20 artists who “photographed the same subjects—-primarily friends, family, and themselves—-over the course of days, months, or years.” The first half of the exhibition will be overly familiar to anyone who’s seen an NGA photography show in the past decade, including works by Alfred Stieglitz,

Paul Strand, Andre Kertesz and Harry Callahan. Only slowly does the notion of periodic portraiture begin to jell and the exhibit gather steam.

Among the highlights: a selection of works by Emmet Gowin (including a dreamy, time-lapsed fantasy portrait of his wife, above); gritty urban portraits by Milton Rogovin; a selection of mirror-aided images by Ilse Bing; a clever transgender trompe l’oeil by Nan Goldin; and a striking, blue-tinted, posthumous print of a self-portrait in which Francesca Woodman looks like a classical column.

A series of 1970s-era experiments by Vito Acconci, Blythe Bohnen, Arnulf Rainer are disappointments; more intriguing are more recent efforts (well, they’re more recent by NGA standards, at least—-they begin in late 1990s). Nikki S. Lee’s photographs of her undercover performances as a Latino, rapper (below), or lesbian are familiar but still impressive; Vibeke Tandberg digitally altered 12 self-portraits with the facial details of friends; and Tomoko Sawada styled herself in 400 separate personas and captured them in a photo booth.

Most stunning is Gillian Wearing’s homage to Robert Mapplethorpe’s famous final self-portrait, the one with a seemingly disembodied head and his hand holding a skull-topped cane. Wearing’s version looks almost exactly like the real thing, because she was wearing a specially crafted Mapplethorpe mask when it was taken. The theme of “serial portraiture” proves more amorphous than one would like, but the inclusion of projects as inspired as Wearing’s do help compensate.

At the National Gallery of Art, 3rd and 7th streets at Constitution Avenue NW. Mondays-Saturdays 10 a.m. to 5 p.m., Sundays 11 a.m. to 6 p.m. To Dec. 31.