  The observed infall of galaxies into the Virgo Cluster puts strong
constraints on the mass of the cluster. A non-parametric fully non-linear
description of the infall can be made with orbit reconstructions based on
Numerical Action Methods. The mass of the cluster is determined to be $1.2
\times 10^{15} M_{\odot}$. The mass-to-light ratio for the cluster is found to
be seven times higher than the mean ratio found across the region within V=3000
km/s.
