  Although far-IR -- mm-wave astronomy has now been developing for several
decades, access to this portion of the spectrum remains difficult and limited.
Relative to their optical-wavelength counterparts, the submillimeter
observatories are both small in units of wavelength and hot in units of photon
energy, which imposes limits on their angular resolution and sensitivity.
Nevertheless, even the modest far-IR and submillimeter observations obtained in
the last two decades have revolutionized our understanding the physics and
chemistry of the ISM, the formation of stars, and the cosmic history of these
processes. The demonstration by COBE that about half of the radiant energy
released in the universe since decoupling comes to us in the submm/far--IR has
further underscored the scientific necessity of observations in this wavelength
regime. The next decade promises even greater discoveries, as new observatories
and detectors are still pushing toward fundamental limits. The paper briefly
outlines some of the exciting capabilities and scientific roles of new
single-dish far--IR -- mm-wave telescopes and their instruments.
