Volcanic ash soils in Mexico cover an approximate surface of 500,000 km2, this represents about 25% of the country. Site quality varies in volcanic soils according to the age of the deposits: in young pyroclastic deposits site quality is poor: soil texture is coarse, causing excessive drainage and low water holding capacity, nitrogen reserve is limited because the organic horizon is thin. During soil development most of these properties improve, however the phosphorus availability becomes a limiting factor for plant growth. Weathering of volcanic ashes produces noncrystalline mineral clays like allophane, and amorphous iron and aluminum oxides. Volcanic ash soils frequently have slightly acidic pH and these clays are positively charged and fix phosphorus. Therefore, volcanic ash soil management is difficult and requires specific considerations. The objective of this study was to analyze site quality changes in different evolutionary stages of volcanic ash soils in Central Mexico. We characterized and classified eight soil profiles across a volcanic chronosequence in order to understand mineralogical chemical changes through time and to evaluate site quality variables. This study contributes to establish characteristic times of evolutionary stages of volcanic ash soils. This information can be applied to implement strategies for ecological restoration as well as to improve forest management and productivity in volcanic ash soils. The study sites are mainly located at the Sierra del Chichinautzin Volcanic Field (SCVF). Here a great number of monogenetic volcanoes of different ages exist. We studied soils formed on the ash covered lava flows of the following volcanic cones: Chichinautzin (1870 years B.P.), Cuespalapa (2800-4700 years B. P.), Tlaloc (6200 years B. P.), Cuautzin (8200 years B. P.), Pelado (10000 years B.P.) and Malalcatepetl (30000 years B. P.). Additionally we included 2 sites from the Sierra de Monte Alto and Monte Bajo (Tertiary) and one site from the Sierra Nevada (1000 years BP). At each one of these sites we described a soil profile. We determined also the growth rates of Pinus montezumae and Abies religiosa by tree ring analysis in conjunction with tree diameter measurements. Preliminary results form field and laboratory analyses are shown to evaluate site quality changes across the chronosequence.