The case for including reach as a key element of program theory.

This paper suggests that there is a need to build reach in the logic models and results frameworks of public health initiatives. A lack of explicit thinking about reach in logic models can lead to problems such as narrow/constricted understanding of impacts chain, favoring of 'narrow and efficient' initiatives over 'wide and engaging' initiatives and biased thinking against equity considerations. An alternative approach described in this paper that explicitly considers reach demonstrates that an explicit description of reach in program theory and results logic depictions can improve equity in health and social systems.