Data in behavioral research usually follow a clustered structure, such as students nested in schools, participants nested in intervention groups, siblings within families, and, in longitudinal studies, repeated measures nested within persons. In this presentation, I will introduce the use of multilevel modeling (MLM) to obtain correct inferences with clustered data, and discuss new research questions that MLM can answer, such as group-specific (or person-specific) coefficients and the decomposition of individual-level and contextual effects. Practical recommendations will be provided on when MLM should be used. In addition, I will discuss some recent advances in MLM for behavioral research, including models for data with complex multilevel structures, effect size estimation, and multilevel bootstrapping.