The rates and activation parameters for the reactions of 2-fluoro-, 2-chloro-, 2-bromo-, 2-chloro-3-methyl-, 2-chloro-5-methyl-, 2-bromo-3-methyl-, 2-bromo-5-methyl-, 2,3-dichloro-, 2,5-dichloro-, 2-chloro-3-nitro-, and 2-chloro-5-nitro-pyridine, and of 2-bromo-, 2-bromo-3-methyl-, and 2-bromo-5-methyl-pyridine N-oxide with potassium methoxide in methanol have been determined and compared. The kinetics of the reaction of 2-bromo-, 2-bromo-3-methyl-, and 2-bromo-5-methyl-pyridine and methoxide ion in dimethyl sulphoxide containing small amounts of methanol have also been determined; the rates were very sensitive to the methanol concentration. The rates were in the order 2-halogeno- > 2-halogeno-3-methyl- > 2-halogeno-5-methyl-, and were dependent upon Eact when the halogen was Br but upon ΔS‡ when it was Cl. The effects of the β-substituent in the pyridine nucleus upon the ortho : para ratios are discussed in terms of their effects upon the energies and entropies of activation.