Creator's Description: In-migration of Han Chinese into Tibet has been a topic attracting many people's attention. But there have been limited sociological surveys conducted in Tibet regarding this issue. Peking University organized a survey in 2005 to study the basic characteristics of temporary migrants in six cities in China's west, including Lha sa. The 2005 Lha sa survey, the first major survey of temporary migrants in Tibet, covered about 1,300 individuals who moved to and worked in Lha sa without formal registration. This paper introduces the basic findings of the survey, including the migrants' age structure, ethnic status, educational background, marital status, current employment, income, housing, and daily consumption. In addition the paper presents data on the migrants' places of origin, dates of migration, how long they plan to stay and work in Lha sa, and their potential future destinations. In general the majority of the temporary migrants in Lha sa came from Han regions. There is a positive correlation between ethnic status and income, but the regression analysis indicates that the income gap between Han and Tibetans is mainly due to the factors of age, education, and whether they are self-employed. Migration selectivity plays an important role among Han migrants who came from far away regions, leaving families at home where they plan to return in two to three years.