TWO YEARS IN the making, Galería de la Raza's "Viology: Cultures of Violence/Violence of Culture" exhibit is one of the most fascinating and effective group shows you'll see this year. The topic is somber, but the contributing artists approach it in all kinds of ways, often leaning more toward the poetic than the gory. Even when you come face-to-face with a dead body, as in Claudia Bernardi's Silently (a photograph of the bones of a mother and her nine-day-old child massacred in El Salvador in 1981), the artist shows it to you through a plate of paraffin wax that shelters the body and keeps prying eyes at a protective distance. Several of the pieces even incorporate an element of humor, like Priscila Monje's Bloody Day photographs, which show her out and about in San Jose, Costa Rica, wearing a pair of pants made out of sanitary napkins. Her menstrual blood is clearly visible, and it effectively turns her ordinary day of errands into a piece of performance art by calling attention to the social taboos surrounding a woman's period. Why does the blood of violence elicit sympathy or even indifference, Monje seems to ask, while the harmless and life-giving kind is perceived as repulsive? The descriptions next to each artwork are indispensable, providing lots of useful background information about the artists and their work, not to mention a kind of crash course in the history of violence in Latin America – corpse-mutilation procedures in Colombia, corrupt Mexico City police officers, Panama's willingness to let former government torturers go unpunished. Besides the photographs, sculptures, installations, and photographs by 20 different artists living in the United States and Latin America, "Viology" also includes video PSAs by San Francisco youth and two digital murals. Tues.-Sat., noon-6 p.m., 2857 24th St., S.F. (415) 826-8009. (Lindsey Westbrook)