Results of analyses of growth processes on two dimensional (2d) crystals are applied to kinetic theories for crystallization of polymers. The purpose is firstly to assess the rate equation methods of calculation which have been used for nucleation (LH) theories, and secondly to estimate free energies of steps σ n on the growth faces of the crystal lamellae in a manner independent of detailed models. A systematic critique is then given of the LH theories, on the basis both of the simulation results and previous work. The range of validity of the calculations used in nucleation theories, using rate equation approaches, is assessed in the light of the effects of fluctuations in step positions and of simulation results (Part 1, ref. 1). The simulation results are given in terms of σ n and the free energy δf for adding stems at niche sites. It is pointed out that, for those nucleation theories which predict l values in line with experiment, δf kT ≲1 . For this range of δf values the density of steps on the surface which is found from simulation results is fairly near the equilibrium values. The predicted step densities in Regime II of (the nucleation theory) is only 2 −1 2 times the equilibrium density (for low step densities). This difference is discussed in terms of a near approach to equilibrium which is mediated by the growth process. Part 1 emphasized the close connection between growth rates and step densities. The dependence of both on σ n is very similar for the simulation results and for the Regime II result (for average spacings between steps greater than about four lattice spacings). For rougher surfaces than this, the growth rate saturates and reaches a plateau at σ n = 0. This is readily interpreted since the step density also saturates. This result is contrasted with that of Regime III (for rough surfaces) which predicts an even stronger dependence of growth on σ n than in Regime II. The discrepancy between the simulation results and Regime III is discussed in detail, and it is pointed out that the prediction of growth in the absence of a thermodynamic driving force is associated with violation of the principle of microscopic reversibility. The applicability of kinetic models is also discussed. Morphological observations, as discussed in more detail elsewhere, seem incompatible with LH theories. The growth rate plots (rate on a log scale against ( TΔT) −1 or against σ n ) are not fully explained by them: only completely straight growth plots can be explained, or smoothly curved convex ones (in terms of a Regime I/II transition, but even for this explanation to be valid the relevant morphological evidence must be disregarded). Concave or sharply kinked growth plots cannot be directly explained in this way. Alternative kinetic models, based on rough growth surfaces and pinning (as a consequence of molecular connectivity) are also discussed briefly in view of the range of experimental evidence. A review is included of other comparisons of experiment with LH theory, including the lack of crystal size effect on the growth rate and the analysis of growth rates of poly(ethylene oxide). It is concluded that the basic hypothesis of LH theories, that σ n is generally large compared with kT and that σ n increases linearly in a steep manner with the lamellar thickness, are not consistent with the experimental evidence.