The Lauwers (Dutch pronunciation: [ˈlʌuʋərs]) is a river in the Netherlands. It forms part of the border between the provinces of Friesland and Groningen. From the 730s to Widukind's defeat in 785, it was part of the border of the Frankish Empire.
The former Lauwerszee and the present-day Lauwersmeer are both named after the river, which as a small stream has its source southeast of the village of Surhuisterveen. Near Gerkesklooster/Stroobos, it crosses the Prinsesmargrietkanaal/van Starkenborghkanaal.
The Lauwers achieves the width of a true river at the place that it gains its tributary, the Oude Vaart, near the Schalkendam. Further along its course, the Lauwers splits into two branches, the Frisian Oude Lauwers and the Zijldiep, in Groningen province.