  A chromospheric age distribution of 552 late-type dwarfs is transformed into
a star formation history by the application of scale height corrections,
stellar evolutionary corrections and volume corrections. We show that the disk
of our Galaxy has experienced enhanced episodes of star formation at 0-1 Gyr,
2-5 Gyr and 7-9 Gyr ago, although the reality of the latter burst is still
uncertain. The star sample birthsites are distributed over a very large range
of distances because of orbital diffusion, and so give an estimate of the
global star formation rate. These results are compared with the
metal-enrichment rate, given by the age-metallicity relation, with the expected
epochs of close encounters between our Galaxy and the Magellanic Clouds, and
with previous determinations of the star formation history. Simulations are
used to examine the age-dependent smearing of the star formation history due to
age uncertainties, and the broadening of the recovered features, as well as to
measure the probability level that the history derived to be produced by
statistical fluctuations of a constant star formation history. We show with
more than 98% level of confidence that the the star formation of our Galaxy was
not constant.
