The parameters of channel models are traditionally determined using measurements. Thus, it is critical to understand the connection between channel measurements and channel models. This will address two important questions: (1) How to use the channel measurements in estimating model parameters? Or how to fit the models to the measurements? And (2) what kind of measurements we need to make to measure the various model parameters. Finally, understanding this relationship will also help in propagating the uncertainties in channel parameters obtained from the measurements in the models. This chapter starts with a general physical model which is a specialization of the general model introduced in Chapter 2 to the practical case of uniform linear arrays. A sampled representation of the physical model serves as a starting point for connecting measurements and models, followed by techniques for high-resolution parameter estimation that can improve on the sampled representation.