  The parity-violating electron scattering community has made tremendous
progress over the last twenty five years in their ability to measure tiny
asymmetries of order 100 parts per billion (ppb) with beam-related corrections
and systematic errors of a few ppb. Future experiments are planned for about an
order of magnitude smaller asymmetries and with higher rates in the detectors.
These new experiments pose new challenges for the beam instrumentation and for
the strategy for setting up the beam. In this contribution to PAVI14 I discuss
several of these challenges and demands, with a focus on developments at
Jefferson Lab.
