Underfill compositions comprise a quinolinol or a quinolinol derivative as a fluxing agent, as an accelerating agent, or as both. The compositions are sufficiently acidic to perform well as fluxes, but not so acidic as to cause premature gelation or corrosion. The compositions also demonstrate higher Tg values than similar compositions that do not contain quinolinol or a quinolinol derivative ##STR00001##