  This work is the continuation of the earlier efforts to apply the mean field
approximation to the world sheet formulation of planar phi^3 theory. The
previous attempts were either simple but without solid foundation or well
founded but excessively complicated. In this article, we present an approach
both simple, and also systematic and well founded. We are able to carry through
the leading order mean field calculation analytically, and with a suitable
tuning of the coupling constant, we find string formation.
