Socioeconomic status is generally associated with better health, but recent evidence suggests that this ‘social gradient’ in health is far from universal. This study examines whether social gradients in smoking and obesity in Mexico – a country in the midst of rapid socioeconomic change – conform to or diverge from results for richer countries. Using a nationally representative sample of 39,129 Mexican adults, we calculate the odds of smoking and of being obese by educational attainment and by household wealth. We conclude that socioeconomic determinants of smoking and obesity in Mexico are complex, with some flat gradients and some strong positive or negative gradients. Higher social status (education and assets) is associated with more smoking and less obesity for urban women. Higher status rural women also smoke more, but obesity for these women has a non-linear relationship to education. For urban men, higher asset levels (but not education) are associated with obesity, whereas education is protective of smoking. Higher status rural men with more assets are more likely to smoke and be obese. As household wealth, education and urbanisation continue to increase in Mexico, these patterns suggest potential targets for public health intervention now and in the future.