It is well-recognized that both improved nutrition and sanitation infrastructure are important contributors to mortality decline. However, the relative importance of the two factors is difficult to quantify since most studies are limited to testing the effects of specific sanitary improvements. This article uses new historical data regarding total investment in urban infrastructure, measured using the outstanding loan stock, to estimate the extent to which the mortality decline in England and Wales between 1861 and 1900 can be attributed to government expenditure. Fixed effects regressions indicate that infrastructure investment explains approximately 30 per cent of the decline in mortality between 1861 and 1900. Since these specifications may not fully account for the endogeneity between investment and mortality, additional specifications are estimated using lagged investment as an instrument for current investment. These estimates suggest that government investment was the major contributor to mortality decline, explaining up to 60 per cent of the reduction in total urban mortality between 1861 and 1900. Additional results indicate that investment in urban infrastructure led to declines in mortality from both waterborne and airborne diseases.B etween 1851 and 1900 mortality rates in Britain declined by almost 20 per cent. Over the same period, local government expenditure on urban infrastructure increased rapidly so that by 1890 spending by local authorities accounted for over 41 per cent of total public expenditure, with much of the money used for water supply and sewers. 1 This simple pattern leads to the natural conclusion that government sanitation expenditure was the driving force behind the improvement in life expectancy. This belief is also supported by evidence from other countries showing that investment in sanitary infrastructure, such as clean water supply, can have positive effects on mortality, both in the present day 2 and historically. 3