Terrestrial climate records for the American Tropics are not abundant, even though they are needed to understand the interaction between regional and basin-wide phenomena, such as the monsoon and ENSO, respectively. Instrumental records are limited to the last century, and are continuous only at few selected locations. Proxy climatic records of longer duration with annual resolution and exact dating are rare, mostly because tropical tree species often form either unclear or undatable growth rings. However, trees at the highest elevations experience much stronger seasonality, and form clear growth layers. We report here the preliminary development of a 300-year tree-ring chronology for Pinus hartwegii from Nevado de Colima, at the western end of the Mexican Neovolcanic Belt. Despite past logging in the area, we were able to locate trees up to 500 years old. Based on the initial processing of 128 collected specimens, crossdating is accurate over the twentieth century. Precipitation and temperature records from Colima stations were quality-controlled and correlated with the tree-ring chronology. From 1950 to 1997, the prewhitened chronology shows a positive response to June rainfall, which represents the start of the summer monsoon. Most trees also show extremely low growth in 1913 and 1914, following the January 1913 Plinian eruption of the Volcan de Colima. Since the same tree species is found on top of high mountains from Mexico to Guatemala, there is potential for developing a network of tropical treeline chronologies