  In this paper we develop a general method for constructing 3-point functions
in conformal field theory with affine Lie group symmetry, continuing our recent
work on 2-point functions. The results are provided in terms of triangular
coordinates used in a wave function description of vectors in highest weight
modules. In this framework, complicated couplings translate into ordinary
products of certain elementary polynomials. The discussions pertain to all
simple Lie groups and arbitrary integrable representation. An interesting
by-product is a general procedure for computing tensor product coefficients,
essentially by counting integer solutions to certain inequalities. As an
illustration of the construction, we consider in great detail the three cases
SL(3), SL(4) and SO(5).
