The goal of this paper is to analyze, by means of detailed numerical simulations, the influence of the partial premixing level and the adequacy of different mathematical submodels on the modeling of co-flow partially premixed methane-air laminar flames. Five levels of premixing of the primary inlet are considered from an equivalence ratio of Phi = infinity (non-premixed flame) to Phi = 2.464. Main flame properties are provided, giving special emphasis to the analysis of pollutant formation. Different mathematical formulation aspects (several chemical mechanisms, radiation effects, mass transport models, and inlet boundary conditions) are tested and validated against experimental data available in the literature. Finite volume techniques over staggered grids are used to discretize the governing equations. A parallel multiblock algorithm based on domain decomposition techniques running with loosely coupled computers has been used to obtain a competitive ratio between computational cost and resources. To assess the quality of the numerical solutions presented in this article, a verification process based on the generalized Richardson extrapolation technique and on the grid convergence index (GCI) has been applied. (C) 2004 The Combustion Institute. Published by Elsevier Inc. All rights reserved.