discriminant validity of in-role and extra-role behavior.
We present empirical support for an expanded,
multidimensional conceptualization of
promotive extra-role behavior (helping and voice).
We demonstrate that individuals in different roles
(self, peer, and supervisor) differentiate these constructs,
and we cross-validate our results at a second
measurement point. Finally, our research extends
prior findings of MacKenzie and colleagues
(1991) and of Werner (1994) to a longitudinal sample
and demonstrates the explanatory power of extra-
role behavior (over and above the effects of control
variables and in-role behavior) in accounting
for variance in employee performance ratings made
six months after the behavior ratings.