  Kant and Laplace suggested the Solar System formed from a rotating gaseous
disk in the 18th century, but convincing evidence that young stars are indeed
surrounded by such disks was not presented for another 200 years. As we move
into the 21st century the emphasis is now on disk formation, the role of disks
in star formation, and on how planets form in those disks. Radio wavelengths
play a key role in these studies, currently providing some of the highest
spatial resolution images of disks, along with evidence of the growth of dust
grains into planetesimals. The future capabilities of EVLA and ALMA provide
extremely exciting prospects for resolving disk structure and kinematics,
studying disk chemistry, directly detecting proto-planets, and imaging disks in
formation.
