  RR Lyrae stars play an important role as distance indicators and stellar
population tracers. In this context the construction of accurate pulsation
models is crucial to understand the observed properties and to constrain the
intrinsic stellar parameters of these pulsators. The physical mechanism driving
pulsation in RR Lyrae stars has been known since the middle of the 20th century
and many efforts have been performed during the last few decades in the
construction of more and more refined pulsation models. In particular,
nonlinear pulsation models including a nonlocal time-dependent treatment of
convection, such as the ones originally developed in Los Alamos in the
seventies, allow us to reproduce all the relevant observables of radial
pulsation and to establish accurate relations and methods to constrain the
intrinsic stellar properties and the distance of these variables. The most
recent results on RR Lyrae pulsation obtained through these kinds of models
will be presented and a few still debated problems will be discussed.
