This paper investigates time allocation decisions in new ventures of female and male entrepreneurs using a model that distinguishes between effects of preferences and productivity on the number of working hours. Using data of 1,158 entrepreneurs we find that the preference for work time in new ventures relates to start-up motivation, propensity to take risk and availability of other income. Productivity of work time relates to human, financial and social capital endowments and the prevalence of outsourcing activities. This study also evaluates actual profit effects 1 year after start-up. We find that on average women invest less time in the business than men. This can be attributed to both a lower preference for work time (driven by risk aversion and availability of other income) and a lower productivity per hour worked (due to lower endowments of human, social and financial capital).