Income shocks and limited upward mobility can undermine people’s well-being and economic prospects. Most cross-country studies on income mobility over people’s lives rely on survey data, but small samples limit detailed analysis by socio-demographic group or segment of the distribution. This paper presents first results of an OECD initiative collecting and harmonising administrative microdata to study income dynamics across countries. Applying rank-rank methods, it measures relative mobility in disposable incomes over five years for working-age people in Austria, Belgium, Canada and Estonia. The paper shows that: i) income persistence is strongest at the bottom and top of the distribution; ii) young people experience larger shifts in income ranks, though not always greater upward mobility; iii) women experience weaker upward mobility than men, particularly in the bottom half of the distribution; and iv) people with tertiary education move up the income ladder, at the expense of those with lower education.