The divorce rate is a poor indicator of marital instability because many marital disruptions never become divorces. This paper provides the first estimate of the rate of marital disruption in the U.S. in 1860 -1948. In the long run, the cohort rate of marital disruption increased from about 10% in the mid-1860s to about 30% in the 1940s. Marital disruption rate was similar to the divorce rate after the Civil War but the two rates diverged wildly in the early 20 th century. In 1900 -1930, the disruption rate was as much as double the divorce rate, implying that perhaps half of all disruptions never reached the court.