The transition between a system behaving completely classically and behaving completely quantum-mechanically is complicated. The two kinds of behaviors can be very different particularly when the system is nonlinear. We know the transition depends on the size of the system, the temperature and environmental effects, and on the nonlinear dynamics, so it is a multi-parameter landscape. But what is the shape of this landscape? In this talk I present evidence for non-monotonicity in the quantum-classical transition in two different systems: A damped driven double-well oscillator, as well as the simple harmonic oscillator. I will also discuss prospects for experimental verification of these predictions.