Soldering flux compositions, solder pastes, and methods of soldering using the same are provided, that exhibit excellent wettability, give highly reliable solder joints, and have superior storage stability. The flux composition contains at least one compound having at least one blocked carboxyl group selected from the group including compound (X) obtained by reaction of a carboxylic acid compound and a vinyl ether compound, compound (Y) obtained by reaction of a carboxylic acid anhydride compound and a hydroxy vinyl ether compound, and compound (Z) obtained by reaction of an acid anhydride and a polyhydric alcohol, followed by addition polymerization with a divinyl ether compound, and the flux composition is non-curing.