  In this paper, we establish sufficient conditions for identifying treatment
effects on continuous outcomes in endogenous and multi-valued discrete
treatment settings with unobserved heterogeneity. We employ the monotonicity
assumption for multi-valued discrete treatments and instruments, and our
identification condition has a clear economic interpretation. In addition, we
identify the local treatment effects in multi-valued treatment settings and
derive closed-form expressions of the identified treatment effects. We provide
examples to illustrate the usefulness of our result.
