Weight reduction is important in the automotive industry. To achieve this, Tailor Welded Blanks (TWB''s) are used: body panels consisting of sheets with different thicknesses and/or materials, welded together and stamped into the desired shape. Aluminium TWB''s have been introduced only recently. Laser welding is a joining technique that shows high potential to produce the required strong yet deformable welds. In this work various aspects of the laser welding of these thin aluminium sheets are treated, like the development of a control system to ensure full penetration keyhole welding and a camera based monitoring system that allows coaxial in-situ process monitoring. Furthermore several models are presented which help to gain a better understanding the welding behavior. Finally five different laser based welding techniques are compared, among which laser welding with cold wire feeding, twin spot laser welding and laser/GMA hybrid welding.