In 2007, the government of Yucatan, Mexico, and the RAND Corporation established a collaborative agreement to design and implement a noncontributory pension program and simultaneously evaluate it through a longitudinal study. This report describes the administration and results of two surveys in Merida, a social observation and a local observation designed to measure socioeconomic characteristics by geographic unit. In particular, it discusses application of observation instruments in May and June 2009 to 112 blocks for 22 basic geostatistical areas to create a social-gap index. The goal was to compare the results of the social-gap index based on local and social observations at the block level with other marginalization and social-gap rates used to target other social-welfare programs in Mexico and to assess the feasibility of targeting delivery of noncontributory pensions for older persons who live in urban areas.