  Using the Hipparcos data, absolute magnitudes and thus the evolutionary
status for the group of lambda Bootis stars were derived. The origin of this
small group of non-magnetic, chemically peculiar stars, still remains a matter
of debate. Using new evolutionary tracks, an age determination could be
provided to distinguish between the two competing theories - the
diffusion/mass-loss and the accretion.
  The results establish the members of this group as objects which are very
close to the Main Sequence. This is supported by Pre-Main Sequence evolutionary
tracks as well as by observational results. This contradicts prior conclusions
that most of these stars are in the middle of their Main Sequence lifetime. The
new results strongly support the predictions of the accretion theory.
