A prototype molecular switch is demonstrated that works on the principle that the local electric field produced by one photogenerated ion pair (D-1(+)-A(1)(-)) can influence the rate constants for photoinduced electron transfer and recombination in a second donor-acceptor pair (A(2)-D-2). Two ultrafast laser pulses were used to control the rate of a photoinduced electron transfer reaction within a molecule that consists of two covalently linked electron donor-acceptor pairs fixed in a linear structure, D-1-A(1)-A(2)-D-2. This type of molecular architecture may lead to the development of electronic devices that function on the molecular length scale.