  We consider the problem of critical gravitational collapse of a scalar field
in 2+1 dimensions with spherical (circular) symmetry. After surveying all the
analytic, continuously self-similar solutions and considering their global
structure, we examine their perturbations with the intent of understanding
which are the critical solutions with a single unstable mode. The critical
solution which we find is the one which agrees most closely with that found in
numerical evolutions. However, the critical exponent which we find does not
seem to agree with the numerical result.
