Impurity concentrations, radiative losses, and particle transport coefficients in tokamak plasmas can be deduced from impurity emissions in the visible, ultraviolet, and x‐ray regions of the spectrum. These measurements rely on impurity transport code modeling of the data; such codes generally require extensive ionization, recombination, and excitation atomic data to link the measured brightnesses to the quantities of interest. Thus, the availability and accuracy of the atomic data play an important role in determining the reliability of the modeling. This paper reviews the use of impurity transport codes to model emissions from the core region of tokamak plasmas, with the emphasis on measurements of impurity transport and on the role of atomic data in these measurements. Following a brief discussion of the general features of impurity transport codes, examples of impurity transport measurements based on measurements of line and continuum emissions in the visible, vacuum ultraviolet, and x‐ray regions are given. These examples represent the major techniques used. The atomic data required in each case are discussed, and areas in which improved data are needed are pointed out.