This paper investigates economic growth in 65 low and lower-middle-income countries from 2010 to 2017. Results from static and dynamic panel data techniques show that foreign direct investment (FDI), capital formation, and labor force significantly increase economic growth while government expenditure decreases growth. Mobile phone subscription reveals no significant impact on growth at aggregate levels. Furthermore, analyses at the income group level reveal substantial differences between the determinants of economic growth in low and lower-middle-income countries. For instance, FDI is a significant predictor of growth in low-income countries, but not in lower-middle-income countries. Similarly, government expenditure and mobile cellular subscriptions are not significant predictors in low-income countries relative to lower-middle-income countries. Interestingly, capital formation and labor force are the two common significant predictors across low and lower-income countries.