Conditional cash transfer (CCT) programs have spread worldwide as a new form of social assistance for the poor. Previous evaluations of CCT programs focus mainly on rural settings, and little is known about their effects in urban areas. This paper studies the short-term (1- and 2-year) effects of the Mexican "Oportunidades" CCT program on urban children/youth. The program provides financial incentives for children/youth to attend school and for family members to visit health clinics. To participate, families had to sign up for the program and be deemed eligible. Difference-in-difference propensity score-matching estimates indicate that the program is successful in increasing school enrollment, schooling attainment and time devoted to homework for girls and boys and in decreasing working rates of boys. (Contains 14 tables, 1 figure and 26 notes.)