This document reports the findings of a research project commissioned by the UK Home Office to investigate select aspects of the better-known conceptual frameworks of radicalisation leading to involvement in terrorism. This project explored: 1) Whether better-known analytical frameworks of radicalisation leading to terrorism involvement can be operationalised and their main concepts made observable through proxy indicators commonly available about individuals convicted for terrorism, who radicalised and offended in the UK; 2) Some frameworks are more easily observable than others given this approach; 3) Some concepts, or categories of concepts, are more observable than others, independent of the analytical frameworks to which they belong.