The general objective of quantitative magnetic resonance imaging (MRI), or parametric mapping, consists of reconstructing synthetic images in which each voxel bears the value of a physical parameter selected a priori. Due to the large degrees of freedom in the choice of acquisition parameters, MRI is versatile and is thus able to quantify different types of physico-chemical parameters. While the steps that result in such mapping are closely dependent on the context, the present chapter attempts to describe, in a natural order, different strategies for obtaining an exploitable parametric map; i.e., the modeling of acquired data in terms of noise and signal, the optimization of the measurement protocol parameters and the actual methods of reconstruction that lead from the acquisition space to the parametric space.