Two classical articles were selected to represent the topic "Milestones in Soil Organic Matter Studies" for the special issue to celebrate the 90th anniversary of Soil Science. The first article, "Comparative Study of Decomposition Rates of Organic Matter in Temperate and Tropical Regions," was authored by H. Jenny, S.P. Gessel, and F.T. Bingham and published in Soil Sci. 68:419-423, 1949. This article, which compared nitrogen and organic matter production and decomposition in temperate and tropical soils, has already been cited in more than 350 journal articles. The citing authors have used the Jenny et al. data to explain their own results in several ways including soil organic carbon increases, litter decomposition rates, dynamic modeling of soil organic matter formation, and ecological and forest ecosystem modeling. The second article, "Turnover of Soil Organic Matter in Some Rothamsted Classical Experiments," was authored by D.S. Jenkinson and J.H. Rayner, Soil Sci. 123:298-305, 1977. This article has had a huge impact on considerations of soil organic matter turnover and has already been cited in upwards of 500 journal articles. The data were fundamental in the progression to the ROTHC model and has led to comparisons of other models such as CANDY, CENTURY, DAISY, and NCSOIL. Without a doubt, the articles by Jenny et al. and by Jenkinson and Rayner on organic amendments to soils, on biomass in soil from plant and microbial sources, and on the turnover of organic matter have contributed enormously to our abilities to predict the long-term stabilities of organic matter in the soil environment. But, there is much work still to be done. At last, we have the technologies that will enable us to understand the compositions and aspects of the structures of the plant and microbial tissues transformed to soil organic components that have degrees of resistance to degradation in the soil environment. Then, when we know better how the compositions/structures of these components are influenced by different soil properties, we will be in a better position to predict more accurately the behavior of organic matter in different soil types under different management regimes.