  I review two different connections between particle theory and early-Universe
cosmology: (1) Cosmic-microwave-background (CMB) tests of inflation and (2)
particle dark matter. The inflationary predictions of a flat Universe and a
nearly scale-invariant spectrum of primordial density perturbations will be
tested precisely with forthcoming maps of the CMB temperature. A stochastic
gravitational-wave background may be probed with a map of the CMB polarization.
I also discuss some other uses of CMB maps. Particle theory has produced two
very well-motivated candidates for the dark matter in the Universe: an axion
and a supersymmetric particle. In both cases, there are a variety of
experiments afoot to detect these particles. I review the properties of these
dark-matter candidates and these detection techniques.
  Much of the material here has appeared before in astro-ph/9712215 and
hep-ph/9710467, but the article here is updated and also expanded considerably.
