To fully realize the advantages of the two-fluid model, accurate prediction of the interfacial area concentration (IAC) is indispensable. Since conventional flow regime–based IAC correlations are not capable of dynamically describing the evolution of interfacial structure, the interfacial area transport equation (IATE) was developed to close the two-fluid model. In the past 30 years, intensive efforts have been made to improve the prediction performance of IATE and extend the experimental database for the IATE benchmark. Recent efforts of the IATE development and benchmark conducted by the Thermal-hydraulics and Reactor Safety Laboratory at Purdue University are reviewed in this paper. This review covers (1) the development of IATE; (2) the experimental database for IATE modeling, including instrumentation development, local measurement data of adiabatic/diabatic two-phase flow, and annular flow characterization; and (3) implementation and evaluation of IATE in one-dimensional/three-dimensional scenarios. Significant progress has been achieved since 2009, and future works required to advance the modeling of IATE are also suggested.