The first lanthanide complex featuring a phosphinidene functional group has been prepared and isolated. Preliminary reactivity studies demonstrate that the lutetium(III) phosphinidene complex, [{2((Pr2P)-Pr-t)-4-Me-C6H3)(2)NLu](2)(mu-PMes)(2), behaves as a phospha-Wittig reagent with aldehydes and ketones to give the corresponding phosphaalkenes. Attempts to use the bulky phosphine H2P-2,4,6-Bu-t(3)-C6H2 to kinetically stabilize a terminal phosphinidene resulted in C-H activation of an ortho-Bu-t group and formation of a phosphaindole.