Until now the assignment of Mesolithic sites to specific assemblage types has been largely based on their microliths, although these tools form less than 3% of the total number of artifacts. A redefinition of Mesolithic assemblage types based on the typological and technological characteristics of the entire industry has been tested on a number of assemblages from Sandy Flanders (Belgium) that are representative of the four typological groups currently identified in the Early Mesolithic of northwestern Europe. The results of these analyses provide new insights into the lithic technology and allow a reassessment of these typological groups. The use of an extensive dating strategy in combination with technological analysis makes it possible to interpret the assemblages both chronologically and functionally and to identify cultural differences among them.