In this paper, we use data from the ‘Families and Social Subjects’ survey conducted by the Italian National Institute of Statistics in 2016 to study the impact of micro- and macro-level economic conditions on first co-residential union formation. We aim to determine if and to what extent the probability of forming the first union is explained by individual labour market positions (e.g. having non-standard employment or not having work), and additionally explore if adverse macroeconomic conditions also play a role. We differentiate by union type—marriage and cohabitation—known to be characterised by different levels of union commitment. We also address potential gender differences by conducting separate analyses on men and women. Our results suggest that while micro- and macro-level economic factors matter in the union formation process, their effect varies by gender and union type. Individual economic vulnerability has a greater impact on marriage than on cohabitation for both men and women. Instead, contextual economic uncertainty plays a relevant role, especially in the transition to cohabitation, regardless of gender, and, to a lesser extent, in the transition to marriage, but only for women.