Although government information technology (IT) projects are often claimed to suffer from cost and schedule overrun, current valid evidence of the magnitude of the problem and its antecedents is difficult to find. To address this gap, we present a mixed-methods study based on 54 Danish government IT projects completed between 2011 and 2020. Using archival data and measures established by Flyvbjerg and colleagues, we find that cost and schedule overrun is substantially lower than reported in previous studies. Qualitative analysis based on interviews and documents in a purposefully selected sub-sample shows that projects are more likely to be completed within budget and schedule if managers actively adopt four key practices: building one team, accommodating uncertainty, rigorous project management and capitalizing on previous domain knowledge. Our findings also suggest that scope reductions may help projects complete within budget and schedule. We discuss theoretical and practical implications for IT project management.