[Questionnaire development in ELSA-Brasil: challenges of a multidimensional instrument].

This article describes the development of the Brazilian Longitudinal Study for Adult Health (ELSA-Brasil) questionnaire. We first address the selection of topics whose contents have to cover the knowledge available on the complex causal network of outcomes and allow comparability with similar studies. Then we deal with the "translation and adaptation of measurement instruments" including neighborhood environment rating scales, depression and anxiety disorder rating scale and a food frequency questionnaire and discuss criteria that guided "theme block sequencing". And finally we focus on the practical importance of "pretesting and pilot studies". The ELSA may provide an original contribution regarding factors that cause or aggravate the outcomes of interest in the Brazilian population, as well as protective factors.