  This paper addresses the motivation, technology and recent results in the
tests of the general theory of relativity (GR) in the solar system. We
specifically discuss Lunar Laser Ranging (LLR), the only technique available to
test the Strong Equivalence Principle (SEP) and presently the most accurate
method to test for the constancy of the gravitational constant, G. The new
Apache Point Observatory Lunar Laser-ranging Operation (APOLLO) will enable
tests of the Weak and Strong Equivalence Principles with a sensitivity
approaching 10e-14, translating to a test of the SEP violation parameter, \eta,
to a precision of ~3x10e-5. In addition, the (v/c)^2 general relativistic
effects would be tested to better than 0.1%, and measurements of the relative
change in the gravitational constant, \dot{G}/G, would be ~0.1% the inverse age
of the universe.
  We also discuss the Laser Astrometric Test Of Relativity (LATOR) mission that
will be able to improve the value of the PPN parameter \gamma to accuracy of 1
part in 10e8 and will measure effects of the next post-Newtonian order (1/c^4)
of light deflection resulting from gravity's intrinsic non-linearity, as well
as measure a variety of other relativistic effects. LATOR will lead to very
robust advances in the tests of fundamental physics: this mission could
discover a violation or extension of GR, or reveal the presence of an
additional long range interaction in the physical law. There are no analogs to
the LATOR experiment; it is unique and is a natural culmination of solar system
gravity experiments.
