Throughout most of art history, there was little concern about the politics of portraiture. Whether the sitter was a paying client or a paid (or unpaid) model, the arrangement with the artist was thought to be straightforward and mutually beneficial. But with modernism, new critical ideas about artistic subjectivity and increased sensitivity to issues of exploitation and objectification significantly complicated this oncesimple genre. As a result, artists today sometimes go to great conceptual lengths to create what they consider to be socially conscious portraits.

For nearly 20 years, John Sonsini has been painting Latino day laborers in the Los Angeles area. He finds them at hiring sites and contracts them at a rate of $20 dollars an hour, often for a period of several weeks. The large full-body portraits that constitute the bulk of his current show at Cheim & Read (there are also five busts) take 20 to 25 days to complete. Mr. Sonsini views the work as collaborative and has each model sign the back of the canvas, beside his own signature.

The subjects, appearing alone or in groups of up to four, are generally viewed straight on, standing upright, arms resting at their sides, fingers or thumbs occasionally looped into pockets. They wear ordinary work clothes — jeans, sneakers, and short-sleeve collared shirts — and have no props other than an occasional knapsack or chair. Their expressions are unassuming and largely inscrutable, though their eyes, which are always wide open, convey vague impressions ranging from confrontation to openness, stoicism to resignation.

The work’s personality comes in no small part from Mr. Sonsini’s distinctive style. The most pronounced inflection comes from his unusual “tilted” perspective, which foreshortens the figures and exaggerates the size of their hands, feet, and faces. The canvases are also notable for the artist’s lush, sensuous brushstrokes and his abstract, color-field backgrounds — gentle swaths of pink, purple, and grassy green.

These painterly surfaces can seem discordant with the issues of economic exploitation that the works conceptually address, but it is precisely this tension between rich texture and subtle politics that makes Mr. Sonsini’s art so intriguing. His paintings are not narrative tableaux with descriptive settings, nor even conventional psychological portraits. While the artist’s careful attention to posture and body, and his detailed exploration of every face, leaves little doubt that each model is a distinct individual, as mysterious and complex as any other, Mr. Sonsini leaves their interior lives largely unexplored, suggesting that some things lie beyond the scope of vision.

Similarly, each title presents nothing but the models’ first names — “Julio,” “Carlos,” “Enrique,” “Elisandro,” and so on — a decision that respects the men’s privacy while also acknowledging their perilous political status. Names without history, disconnected to a past, they remain, even when presented so plainly to us, partially hidden. The humanity of Mr. Sonsini’s portraits lies in the way he forces us to recognize not only his subjects’ dignity, but also the complicity of silence between day laborers and more fortunate Americans that keeps us from knowing them better.

If economic inequality is a primary consideration of Mr. Sonsini’s portraits, Joe Ovelman’s newest work addresses issues of racial prejudice. For “Rosa Parks 381” (2007), the centerpiece of his show at Oliver Kamm/5BE Gallery, the artist approached selfidentifying African-Americans in various locations around New York and made the following offer: In exchange for a signed Polaroid portrait of them, they would take a photo of him, sign it, and give it to him. The resulting installation contains 381 photographs of the artist, who is white, each signed by its otherwise anonymous amateur photographer. The number 381 corresponds to the number of days of the Montgomery, Ala., bus boycott, and the installation is arranged like a calendar, with photographs to be read seven across and then down to the next row.

The work is inspired by a James Baldwin quotation, “I’ll be black for as long as you tell me that you are white,” although here the equation is reversed. Indeed, the real focus of this work and the uneven show to which it belongs is Mr. Ovelman’s racial self-consciousness — how he feels his own whiteness most acutely in racially charged situations, whether confronting racial slurs or asking someone with dark skin if he or she self-identifies as an African-American.

Interesting though it is, the heavy-handed concept of “Rosa Parks 381” fails to yield a fully coherent, visually satisfying work. Unlike Mr. Sonsini, who manages to convey considerable particularity to his figures, even as he navigates competing claims of stereotype and individuality, Mr. Ovelman’s composite (self-)portrait does not challenge viewers to see beyond the well-intentioned, lighthearted, sometimes goofy, white guy who appears in all the photos.

Sonsini until February 10 (547 W. 25th St., between Tenth and Eleventh avenues, 212-242-7727); Ovelman until February 10 (621 W. 27th St., between Eleventh and Twelfth avenues, 212-255-0979).