Molecular distributions of macromolecular materials are currently described by lumped parameter models which require integration of complex, nonlinear functions for each degree of polymerization. Inasmuch as average degrees of polymerization for commercial polymers frequently are in the range of five thousand, a simulation of molar or mass distributions as a function of degree of polymerization and time is a difficult, but an achievable task. However, explicit, experimental utilization of molecular distribution data to update kinetic constants and to extensively test mechanisms utilizing current theoretical descriptions is, perhaps, insurmountable, or at least foolhardy. An alternate formulation, based on the Principle of Conservation of Population, is presented. This distributed parameter model is readily solved by the Method of Characteristics, yielding dynamic response surfaces. In fact, for n-butyl lithium initiated polymerizations of styrene, a single integration generates the ground curve which passes through the origin. Additional ground curves, are readily generated algebraically through translations along the degree of polymerization axis. The dependent variable, population density of carbanions, is described by a simple exponential time decay along a characteristic path. An algorithm incorporating the Method of Characteristics is presented for the distributed parameter model. Substantial theoretical simplifications and numerical cost savings are realized in simulating molecular response surfaces as functions of time and degree of polymerization. A second objective is to develop experimental and theoretical techniques that are amenable to the incorporation of molecular distribution data into kinetic analysis. The presented theoretical description yields relationships that are reducible to simple, graphical interpretations. Experimentally measured variables include initiator concentration, monomer concentration, and molecular distribution data. Experimental molar distributions for n-butyl lithium initiated styrene polymerizations are observed to correlate, allowing for the calculation of absolute rate constants. Frequency factors and activation energies for initiation, propagation and dimeric polystyryl anion association are: Activation energy Frequency factor Initiation 10,500 1·1 × 10 5 Propagation 2,000 3·1 × 10 2 Association −31,200 1·0 × 10 2 The unit for time is minutes, concentrations are molar, activation energies are expressed in calories/g mol, temperature is in oK and rates are mol/l/min.