The phenomena of heat transfer with phase change are the subjects of this chapter. The first part of the chapter studies the condensation of vapor on cold surfaces, where the condensation in the form of a laminar descending film on vertical surfaces is modeled following the pioneering work of Nusselt. Practical working expressions are presented for the turbulent and wavy regimes on tubes and tube banks. Droplet condensation is the subject that concludes the study of condensation. The second part of the chapter studies the boiling phenomenon, with the first topic addressed being pool boiling and its boiling curve that displays significant pieces of information such as the onset of nucleate boiling (ONB), characterized by the formation of individual bubbles, followed by the formation of bubble columns and film boiling (of vapor). The subject is presented in detail along with practical working equations and its proper modeling. It also presents the effect of the hysteresis of the boiling curve. The chapter concludes with the presentation of convective heat transfer boiling and the modeling resulting in expressions for calculating the critical heat flux (CHF).