Quasilinear utility functions, i.e. functions excluding an income or wealth effect for one variable, play an important role in modern economics. They often permit the reduction of the complexity of a given problem or provide the necessary input for higher order problems. The analysis proceeds as follows: First, the standard function specifies strong additivity which is generalized to strong separability. Second, the variable bearing the income effect is replaced by a linear homogenous function of many variables. Third, given the second order conditions for an optimum, the function of the variable subject only to a substitution effect can be extended to a strictly concave function of several variables.