We analyze the effects of government spending in a New-Keynesian model with search and matching frictions featuring endogenous growth through learning-by-doing and skill loss from longterm unemployment. We show that medium-run and long-run output and unemployment multipliers are much larger compared to the standard model that abstracts from endogenous growth and skill loss. In our model the aggregate effect of a temporary fiscal stimulus is amplified via the skill loss channel through lower training costs. Via the learning-by-doing channel, it leads to hysteresis in human capital accumulation and thereby output. These results hold for alternative forms of fiscal financing (lump-sumtax, distortionary tax and government debt) as well as alternative labor market institutions (US and Europe).