<p>This paper reviews research topics that I have had the fortune to explore with Loet Leydesdorff over the past decade. What initially seemed to be different areas of research have eventually been brought together into a unified framework for a theory of meaning in inter-social communication. The sociology of communication laid the foundations for a theory of meaning, but it has largely remained pure theorizing, as it does not provide any tools for operationalization and measurement. At the same time, the problem of operationalizing communication in social systems requires a different approach than that used in Shannon’s mathematical theory of communication. It is to the credit of Loet Leydesdorff that he has succeeded in reconciling these two perspectives, making the theory of meaning accessible to quantitative calculations. This potentially opens up a wide range of applications for the theory. Here I outline the cornerstones and structure of Loet’s theory of meaning, as well as its further development and promising applications.</p>