  In this talk I review some of the key questions that weak lensing
observations of clusters can potentially answer, and sketch the progress that
has been made to date in extracting quantitative estimates of masses and
density profiles. A major difficulty in interpreting these measurements is the
diverse methods that have been used to calibrate the shear-polarization
relation, none of which are completely satisfactory. I describe some recent
developments in the theory of weak lensing calibration. I then present some
results from the UH8K camera and discuss their implication for cosmology.
Finally, I outline a new strategy for obtaining high resolution optical imaging
from the ground using an array of small telescopes, and describe how such an
instrument can greatly improve the power of weak lensing observations

Astrophysics