  Major improvements in models of chemically peculiar stars have been achieved
in the past few years. With these new models it has been possible to test
quantitatively some of the processes involved in the formation of abundance
anomalies and their effect on stellar structure. The models of metallic A (Am)
stars have shown that a much deeper mixing has to be present to account for
observed abundance anomalies. This has implications on their variability, which
these models also reproduce qualitatively. These models also have implications
for other chemically inhomogeneous stars such as HgMn B stars which are not
known to be variable and lambda Bootis stars which can be. The study of the
variability of chemically inhomogeneous stars can provide unique information on
the dynamic processes occurring in many types of stars in addition to modeling
of the evolution of their surface composition.
