Life expectancy in England & Wales has diverged from that of its high-income peers since 2011, raising concerns that the country may become an international laggard like the United States (US). Using the contour method, we decompose gaps in life expectancy between England & Wales and 20 individual high-income countries for males and females in 2019 into: (a) pre-existing differences in age- and cause-specific death rates in 2011; and (b) diverging trends in these rates between 2011 and 2019. Focusing on trends, we find that external mortality at young-to-middle ages, cardiometabolic mortality at middle-to-older ages, and dementia mortality at older ages contributed most to life expectancy gaps. Although England & Wales and the US shared adverse trends in cardiometabolic and external mortality, England & Wales experienced larger life expectancy gains. Our findings underscore the urgency of improving population health in England & Wales to avoid life expectancy falling further behind.