This is a proposal to continue a unique micro-level study of the reciprocal relations between population processes (family formation and migration) and environment (land use, flora diversity, agricultural practices, and consumption of natural resources) in the Nepalese Himalayas. This study has already collected detailed micro-level data on both population and environment. The environmental data feature direct observation measurement (with tape measures) of land use in 151 neighborhoods and detailed counts (by hand) of flora species from more than 300 plots surrounding those neighborhoods. Both flora and land use data were collected twice, four years apart (winter 1996 and winter 2000), from exactly the same locations. The population data feature monthly records of births, deaths, marriages, divorces, in-migration, out-migration, and contraceptive use for every individual living in those 151 neighborhoods, including migrants, during the intervening four year period. Additional data from the same neighborhoods include histories of contextual change over time, individual histories for all residents age 15- 59, and household-level measures of agricultural practices and consumption of natural resources. These data provide an unprecedented opportunity to investigate population-environment relationships. The primary aim of the continuation proposed here is to analyze existing data to address four specific questions: 1) To what extent do marriage timing, household fission, childbearing, and migration influence land use and flora diversity? 2) To what extent do land use and flora diversity influence marriage, household fission, childbearing, and migration? 3) To what extent do agricultural practices and consumption patterns link population to environmental outcomes? and 4) To what extent are the observed relationships between population and the environment produced by exogenous changes in the social, economic and institutional context? Our second aim is to extend the data forward in time to provide a truly exceptional data resource for understanding the micro-level relationships between population and environment. Our third aim is to systematically apply ethnographic methods to gather information to redesign our survey measures of the factors linking population and the environment, and to improve our models of these processes. Although the demands of the project we propose are substantial, we have assembled an uncommonly rich team of researchers including leading experts in each substantive and methodological area needed to successfully implement this innovative and ambitious project.