  A general discussion of the renormalization of the quantum theory of a scalar
field as an effective field theory is presented. The renormalization group
equations in a mass-independent renormalization scheme allow us to identify the
possibility to go beyond the renormalizable $\phi^{4}$ theory without losing
its predictive power. It is shown that there is a minimal extension with just
one additional free parameter (the mass scale of the effective theory
expansion) and some of its properties are discussed.
