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We present a new analysis of the Delta I = 1/2 rule in K --> pi pi decays andthe B_K parameter. We use the 1/N_c expansion within the effective chirallagrangian for pseudoscalar mesons and compute the hadronic matrix elements atleading and next-to-leading order in the chiral and the 1/N_c expansions.Numerically, our calculation reproduces the dominant Delta I = 1/2 K --> pi piamplitude. Our result depends only moderately on the choice of the cutoff scalein the chiral loops. The Delta I = 3/2 amplitude emerges sufficientlysuppressed but shows a significant dependence on the cutoff. The B_K parameterturns out to be smaller than the value previously obtained in the 1/N_capproach. It also shows a significant dependence on the choice of the cutoffscale. Our results indicate that corrections from higher order terms and/orhigher resonances are large for the Delta I = 3/2 K --> pi pi amplitude and the(|Delta S| = 2) K^0 -- anti K^0 transition amplitude.Comment: 50 pages, LaTeX, 13 eps figure

New analysis of the $\Delta I = 1/2$ rule in kaon decays and the $\hat{B}_K$ parameter