Leptonic D and D_s Decays near c-cbar Threshold

We present recent results from the CLEO Collaboration on leptonic decay rates of $D$ and $D_s$ near $c\bar{c}$ production threshold. From these decay rates, we extract the decay constants, f_D = (222.6±16.7^{+2.8}_{-3.4}) MeV, f_Ds = (274±10±5) MeV, and the ratio f_Ds/f_D = 1.23±0.11±0.03.