Background: Many studies have reported a social class gradient within overweight prevalence (1-4). Additionally, cross-country comparisons report high overweight trends and a change in food consumption patterns in countries affected by an economic crisis (5-11). The aim of this study was to assess the association between social class and recession on obesity levels in 3-year-old Irish children. Methods: The population-based infant cohort of the national Growing Up in Ireland (GUI) study was used. Prevalence rates of overweight and obesity were calculated and logistic regression models, adjusting for confounders, were used to examine the relationship between social class, effects of the recession and childhood obesity. Results: In 2008, 19.5% of 9-month-olds were obese and 19.4% overweight increasing to 22.7% and 20.4%, respectively by 2011 when the infants were 3 years old (World Health Organization (WHO) criteria). The prevalence of obesity increased by 2.3% to 10.1% for various social classes (unadjusted). However, adjusting for confounders, there was no evidence of a difference in obesity of 3-year-old children across social classes. There was evidence that obesity was 22-27% higher for families who perceived a very significant crisis effect on their family, compared with those significantly affected. Conclusion: Increases in obesity were found to be significantly associated with perceived recession effects on the family, but not with social class. Policy makers should be aware that in times of economic downturn, public health efforts to promote healthy weight are needed at a population level rather than for specific social classes.