Digital innovations enable tracking tools and quantification technologies to be applied in any field. Professions have integrated new practices, adapted and evolved as consequence. In this work I analyse how a particular segment of communications practitioners use digital metrics. Public Relations (PR) professionals have historically been reluctant to quantitative evaluation; their expertise residing in an intangible influence, executed through relationship and persuasive messages. However, the proliferation of social media and webometrics pushed the development of a new segment specialised in measurement and evaluation, and they are fostering their own codes and good practices. Thanks to a set of interviews, observation and trade press analysis, I identified these codes and good practices to achieve what they call the “meaningful measurement” and the failures that lead to a “meaningless measurement”. This includes four main rules for its members to follow: the rule of purpose, the rule contextuality, the rule of causality and, finally, the rule of research and transparency.