We consider the contribution of the intensive margin of labor supply (hours worked above zero) to the gender wage gap across four economies (Germany, France, US, UK) over a long time-horizon. We first build a model in which firms offer two wage contracts – one that pays a fixed wage but allows workers to choose their preferred number of hours up to “full time”, and a second in which wages are relative to imperfectly observable productivity but hours can be limitless. The former includes part- and full-time work, while the latter represents a class of workers who often must supply very long hours but who can then earn potentially unlimited remuneration. We then apply a Oaxaca decomposition for part-, full-, and over-time workers to observe the relative contribution of sorting and remuneration across these hours “regimes” over time and across countries. Through this, we show that while female employment in over-time work increased and the gender wage decreased, this was not driven by increasing selection but rather by a decrease in the unexplained portion of the wage gap over time. We conclude by considering the contribution of unions and labor market flexibility to these cross-country differences.