On Single-Index Models. -- High Dimensional Data Yan Yu Abstract: Single-index models are an important tool for multivariate nonparametric estimation. By reducing the dimensionality from that of a general covariate vector to a univariate index, single-index models avoid the so-called "curse of dimensionality." Firstly, I will give a brief overview of single-index models, focusing on generalized partially linear single-index regression models by a penalized spline approach (P-spline). Secondly I will introduce single-index varying coefficient models for both regression and dependent data, where we focus on the estimation, inference, and forecasting of the single-index coefficient models under dependence. Finally I will discuss some most recent research for single-index conditional quantiles using local linear estimation. Related working papers are downloadable from http://statqa.cba.uc.edu/~yuy/index.htm