Abstract. Quantile regression (QR) is a principal regression method for analyzing the impact of covariates on outcomes. The impact is described by the conditional quantile function and its functionals. In this paper we develop the nonparametric QR-series framework, covering many regressors as a special case, for performing inference on the entire conditional quantile function and its linear functionals. In this framework, we approximate the entire conditional quantile function by a linear combination of series terms with quantile-specific coefficients and estimate the function-valued coefficients from the data.We develop large sample theory for the QR-series coefficient process, namely we obtain uniform strong approximations to the QR-series coefficient process by conditionally pivotal and Gaussian processes. Based on these two strong approximations, or couplings, we develop four resampling methods (pivotal, gradient bootstrap, Gaussian, and weighted bootstrap) that can be used for inference on the entire QR-series coefficient function.We apply these results to obtain estimation and inference methods for linear functionals of the conditional quantile function, such as the conditional quantile function itself, its partial derivatives, average partial derivatives, and conditional average partial derivatives.Specifically, we obtain uniform rates of convergence and show how to use the four resampling methods mentioned above for inference on the functionals. All of the above results are for function-valued parameters, holding uniformly in both the quantile index and the covariate value, and covering the pointwise case as a by-product. We demonstrate the practical utility of these results with an empirical example, where we estimate the price elasticity function and test the Slutsky condition of the individual demand for gasoline, as indexed by the individual unobserved propensity for gasoline consumption.Date: first version May, 2006, this version of August 1, 2017. The main results of this paper, particularly the pivotal method for inference based on the entire quantile regression process, were first presented at the NAWM Econometric Society, New Orleans, January, 2008 and also at the Stats in the Chateau in September 2009. We are grateful to Arun Chandraksekhar, Ye Luo, Denis Tkachenko, and Sami Stouli for careful readings of several versions of the paper. We thank Gary Chamberlain, Andrew Chesher, Holger Dette, Roger Koenker, Tatiana Komarova, Arthur Lewbel, Oliver Linton, Whitney Newey, Zhongjun Qu, and seminar participants at the Econometric Society meeting, CEME Econometrics of Demand conference, CEMMAP master-class, CIREQ High-Dimensional Problems in Econometrics conference, ERCIM conference, ISI World Statistics Congress, Oberwolfach Frontiers in Quantile Regression workshop, Stats in the Chateau, Austin, BU, CEMFI, Columbia, Duke, Harvard/MIT, NUS, Rutgers, Sciences Po, SMU, Upenn, Virginia, and Yale for many useful suggestions. We are grateful to Adonis Yatchew for giving us permission to use the data set i...