This thesis reconstructs precipitation variability in the southern Canadian Cordillera over the past 3-400 years using dendroclimatological techniques. Fifty-three total ring-width (RW) chronologies and 28 earlywood (EW) and latewood (LW) chronologies have been developed from open-grown, low-elevation stands of Pseudotsuga menziesii (Douglas-fir) and Pinus ponderosa (ponderosa pine) across the southern Canadian Cordillera. Sample sites range from the eastern flanks of the B.C. Coast Ranges and the Canadian Rockies and extend from the Canada-U.S. border to the northern limits of both species. The chronologies range from 123-691 years and, on average, have a strong within-chronology common signal. Maximum correlations for RW in both species occur with annual precipitation totals. EW width is most consistently and strongly correlated with precipitation in the previous July and August whereas LW width is more strongly related to precipitation in the current June and July. RW, EW and LW chronologies from both species are used to develop 13 annual (prior July to current June) precipitation reconstructions for sites in the southern Canadian Cordillera. The reconstructions range in length from 165 to 688 years, pass a series of verification tests conducted using independent data and capture between 39 and 64 percent of the variance in the instrumental records used to develop the models. Coincident, prolonged intervals of dry conditions are estimated for the years: 1625-1650, 1716-1732, 1756-1760, 1793-1800, 1839-1860, 1868-1875, 1889-1897, 1917-1941, 1968-1979 and 1985-1989. Wet conditions occur in the majority of reconstructions for the years: 1942-1960, 1898-1916, 1880-1890, 1800-1830, 1778-1789, 1750-1755, 1689-1700 and 1595-1615. Correlations with a gridded precipitation dataset provide additional verification of the quality of the reconstructions and indicate that, taken together, the reconstructed series are related to conditions over much of the southern Canadian Cordillera. Map patterns representing common early summer (MJJ) circulation anomalies at the 1000 mb level in the northern Hemisphere appear to be related to dry and wet years in instrumental and reconstructed precipitation records.