Emerging out of the “reproducibility crisis” in science, metascientists have become central players in debates about research integrity, scholarly communication, and science policy. The goal of this article is to introduce metascience to STS scholars, detail the scientific ideology that is apparent in its articles, strategy statements, and research projects, and discuss its institutional and intellectual future. Put simply, metascience is a scientific social movement that seeks to use the tools of science- especially, quantification and experimentation- to diagnose problems in research practice and improve efficiency. It draws together data scientists, experimental and statistical methodologists, and open science activists into a project with both intellectual and policy dimensions. Metascientists have been remarkably successful at winning grants, motivating news coverage, and changing policies at science agencies, journals, and universities. Moreover, metascience represents the apotheosis of several trends in research practice, scientific communication, and science governance including increased attention to methodological and statistical criticism of scientific practice, the promotion of “open science” by science funders and journals, the growing importance of both preprint and data repositories for scientific communication, and the new prominence of data scientists as research makes a turn toward Big Science.