This paper examines the linkages between population growth and standard-of-living growth in 21 countries over the period of 1870-2013. We apply the bootstrap panel causality test proposed by Kónya (Econ Model 23:978-992, 2006), which accounts for both dependency and heterogeneity across countries. We find one-way Granger causality running from population growth to standard-of-living growth for Finland, France, Portugal, and Sweden, one-way Granger causality running from standard-of-living growth to population growth for Canada, Germany, Japan, Norway and Switzerland, two-way causality for Austria and Italy, and no causal relationship for Belgium, Brazil, Denmark, Netherlands, New Zealand, Spain, Sri Lanka, the UK, the USA, and Uruguay. Dividing the sample into two subsamples due to a structural break yields different results over the two periods of 1871-1951 and 1952-2013. Our empirical results suggest important policy implications for these 21 countries as the directions of causality differ across countries and time period.