  We present a new technique based on two-pathway optical coherent control for
the sensitive detection and precise measurement of highly-forbidden transitions
in atomic systems. Specifically, we show that ($\omega$, 2$\omega$) coherent
control can be applied to the measurement of the magnetic dipole and
electroweak parity nonconserving amplitudes in atomic cesium, with the
principal advantage of reduced systematic errors related to field reversals
often encountered in previous measurements of these effects. We present a
complete analysis in one specific geometry, and discuss prospects for improved
laboratory determinations of these weak transition amplitudes.
