  Two rival hypotheses have been proposed for the origin of the compact radio
flux observed in radio-quiet quasars (RQQs). It has been suggested that the
radio emission in these objects, typically some two or three orders of
magnitude less powerful than in radio-loud quasars (RLQs), represents either
emission from a circumnuclear starburst or is produced by radio jets with bulk
kinetic powers 10^3 times lower than those of RLQs with similar luminosity
ratios in other wavebands. We describe the results of high resolution
(parsec-scale) radio-imaging observations of a sample of 12 RQQs using the Very
Long Baseline Array (VLBA). We find strong evidence for jet-producing central
engines in 8 members of our sample.
