Many contentious elections end in disputes about alleged fraud, irregularities, and malpractices. How do we know when these claims are valid and when they are false complaints from sore losers? This article describes a new dataset developed by the Electoral Integrity Project. Based on a survey of election experts, the research provides new evidence to compare how national contests around the world are meeting international standards of electoral integrity. The questionnaire includes 49 key indicators clustered into 11 stages of the electoral cycle, as well as generating an overall summary Perception of Electoral Integrity (PEI) 100-point index. The evidence displays high levels of external validity, internal validity, and legitimacy. The PEI datasets allow researchers to gauge the perceived quality of elections worldwide. This study summarizes the PEI’s research design, compares the quality of elections around the globe, and illustrates how electoral integrity is linked with both democracy and development.