In many academic disciplines, there are promising discoveries and valuable information, which have the potential to improve lives but have not been transferred to or taken up in ‘real world’ practice. There are multiple, complex reasons for this divide between theory and practice—sometimes referred to as the ‘know-do’ gap—and there are a number of disciplines and research fields that have grown out of the perceived need to close these gaps. In the field of health, Knowledge Translation (KT) and its related research field, Implementation Science (IS) aim to shorten the time between discovery and implementation to save and improve lives. In the field of humanitarian development, the discipline of Communication for Development (ComDev) arose from a belief that communication methods could help close the perceived gap in development between high- and low-income societies. While Implementation Science and Communication for Development share some historical roots and key characteristics and IS is being increasingly applied in development contexts, there has been limited knowledge exchange between these fields. The aim of this paper is to provide an overview of the characteristics of IS and ComDev, analyze some key similarities and differences between them and discuss how knowledge from each could help inform the other to more effectively achieve their common goals.