  The basic facts of charge symmetry breaking (CSB) phenomena are reviewed. The
relevance of CSB to parity-violating electron-proton scattering experiments
that seek to extract strange elastic form factors is discussed.
Experimentalists have stated and written that the current uncertainty in our
knowledge of CSB limits the ability to push further on the strange form
factors. I discuss recent calculations using relativistic chiral perturbation
theory and realistic values of strong coupling constants which show that the
uncertainties due to lack of knowledge of CSB are at least ten times smaller
than present experimental uncertainties. Estimates of CSB effects are made for
the JLab Qweak and Mainz P2 experiments.
