  Cosmological implications of the observed large-scale peculiar velocities are
reviewed, alone or combined with redshift surveys and CMB data. The latest
version of the POTENT method for reconstructing the underlying
three-dimensional velocity and mass-density fields is described. The initial
fluctuations and the nature of the dark matter are addressed via statistics
such as bulk flow and mass power spectrum. The focus is on constraining the
mass density parameter $\Omega$, directly or via the parameter $\beta$ which
involves the unknown relation between galaxies and mass. The acceptable range
for $\Omega$ is found to be $0.4-1.0$. The range of $\beta$ estimates is likely
to reflect non-trivial features in the galaxy biasing scheme, such as scale
dependence. Similar constraints on $\Omega$ and $\Lambda$ from global measures
are summarized.
