This article is designed to give the reader a conceptual, nontechnical overview of estimation and model fit issues in multilevel modeling (MLM). The process of MLM generally involves fitting a series of multilevel models that increase in complexity. When conducting multilevel analyses, it is important to balance the need for complexity and the need for parsimony. Therefore, having a solid understanding of issues related to model fit is essential in MLM. To really understand model fit, it is necessary to have at least a conceptual understanding of estimation issues. In this article, the authors introduce topics related to the estimation of multilevel models and the determination of model fit. They introduce techniques for model specification and comparison and provide recommendations for their application.