A new secular study has concluded that the Second Vatican Council (Vatican II, 1962–1965) triggered a significant decline in Catholic Mass attendance worldwide. The working paper, titled Looking Backward: Long‑Term Religious Service Attendance in 66 Countries, was published in July 2025 by the National Bureau of Economic Research (NBER) and authored by Robert J. Barro, Sarah Dewitte, and Laurence R. Iannaccone (NBER).
Key Findings
The study examined religious service attendance rates in 66 countries using retrospective data from the International Social Survey Program and other historical surveys, tracking trends as far back as 1920. It found that in countries where the population was at least 50% Catholic—such as Ireland, Italy, France, Brazil, the Philippines, and Mexico—monthly adult attendance began a sustained decline immediately after 1965, the final year of Vatican II.
The authors reported that Catholic service attendance fell by roughly four percentage points per decade between 1965 and 2015, a decline that did not occur in non‑Catholic Christian countries (NBER Study). The paper states:
“Compared to other countries, Catholic countries experienced a steady decline in the monthly adult religious service attendance rate starting immediately after Vatican II.”
This decline amounted to more than 20 percentage points over the studied period, relative to other countries and to non‑Catholic Christian nations.
Possible Explanations
The study itself does not single out specific documents from Vatican II but aligns with previous hypotheses by sociologists such as Andrew Greeley, suggesting that the Council’s reforms may have unintentionally weakened Catholic practice.
- Liturgical changes introduced in the mid‑1960s included Mass celebrated facing the people, simplified rites, and the removal of certain traditional prayers. These adjustments, meant to encourage participation, may have instead disrupted the sense of sacred continuity (LifeSiteNews).
- Doctrinal uncertainty in the years following the Council, particularly surrounding debates like those leading up to Humanae Vitae in 1968, likely contributed to a perception of instability within the Church (Complicit Clergy).
- Cultural effects identified by historian Guillaume Cuchet show that post‑1965 France and other Catholic nations experienced an unprecedented collapse in practice once the traditional framework was altered (LifeSiteNews).
Why This Study Matters
Because the study is produced by NBER, a respected economic research institution with no ecclesiastical affiliation, it carries weight as a neutral, data‑driven analysis. Its global scope—spanning almost a century of data—suggests that Vatican II had a unique impact on Catholic practice rather than simply reflecting global secularization (NBER).
The research demonstrates a clear and measurable drop in Catholic Mass attendance that began after Vatican II and continued steadily for decades. While the study does not claim that Vatican II’s theological aims were inherently flawed, it concludes that the reforms coincided with—and likely triggered—a lasting decline in participation in Catholic worship worldwide.
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