Specimens of three Al-Mg-Si alloys, 6060, 6005 and 6082, were solution heat treated, stored at different temperatures for different time, and artificially aged. Properties were measured before and after artificial ageing. The natural ageing response of the alloys is dependent on the storage temperature. Decreasing storage temperature leads to a delayed onset of natural ageing, but also to a higher strength after prolonged ageing, particularly for lean alloys such as 6060. The temperature and time of intermediate storage between solution heat treatment and artificial ageing has a significant effect on the strength of the artificially aged material. For the 6005 and 6082 alloys the processes that take place during natural ageing lead to a reduced strength after artificial ageing.