Political ideologies are foundational to a broad range of social science fields such as Political Science, and Social and Political Psychology. Ideologies aid individuals navigate the complex socio-political world by offering an organization of values, justifying social arrangements, and explaining power relations. While scholars use diverse and wide-ranging approaches, all have in common the measurement of an individual’s political ideology. We sought to investigate this practice for which we conducted an exhaustive literature review of over 400 scientific articles, spanning from the 1930s to 2020s, across a wide range of social sciences’ subfields. We found and catalogued more than 60 unique ideological instruments measuring the same construct: ideology. However, validity evidence such as statistical/psychometric technique, extraction and rotation method were sparingly reported, with only a few studies reporting more than one type of criteria.We found a high frequency of incomplete reporting of the items used, and substantial variance in scoring and scale type -even within seemingly identical scales (e.g., Wilson & Patterson's C-scale).About half of published ideological instruments failed to provide any validation evidence in its favor, and from the remaining, only a third had reported being developed or validated.Results show that most ideological instruments were either on-the-fly measures or an ad-hoc combination of items present in existing, publicly available surveys. Our research suggests the literature isn't transparent about the measures it uses, and it's not conducive to replication attempts.These characteristics preclude the accumulation of scientific knowledge, and likely pose a serious threat to the comparability and generalizability of published findings.