The slope inequality for fibered surfaces plays a central role in the geography of algebraic surfaces of general type and is closely related to the positivity of divisors on the moduli space of curves. In this talk, I will first explain the relationship between the slope of a fibered surface and the slope of effective divisors on the moduli space of curves. I will then present the main result on the slope inequality for fibered surfaces whose general fiber is a general curve. Finally, I will discuss an application of this result to the slope of effective divisors on the moduli space of curves.