It has become a natural mandate to the particle physics community to look b
eyond presently active and approved high-energy accelerators for precision
work at the edge of, and beyond, the Standard Model. We stress the mandate
for complementary use of both charge modes of the Electron Collider, e(+)e(
-) and e(-)e(-). Choosing a few illustrative examples, we attempt to set th
e stage for technical developments needed to define and execute the key exp
eriments using two incoming electron beams.