The paper describes research work that has been carried out to reduce the viscous drag of transport aircraft wings by controlling the turbulent contamination on the attachment line. Laminar leading edges will reduce the boundary layer thickness downstream and thus reduce drag. This scenario was postulated by M. Gaster in a paper presented to the AIAA Seattle conference in 2008. The effect of maintaining a laminar attachment line on the overall flow on a wing has been modeled and drag reductions calculated. These values are compared with wind tunnel measurements of viscous drag of a wing with both laminar and turbulent attachment lines.