The concept of effective protection was originally formulated under the assumption of fixed intermediate input coefficients. This paper investigates the difficulties that arise when these coefficients may vary. The article distinguishes two goals of effective rates which can both be met by a single measure when input coefficients are fixed but which necessitate distinct measures when they are variable. The paper attempts to define precisely and derive rigorously in a general equilibrium setting measures of effective protection, and discusses the relation of these measures to the existing literature and the implications of the resulting formulas for applications of the concept.