During muscle development, the laminin-specific ␣7 integrin is alternatively spliced in the putative ligand-binding domain to yield either the ␣7X1 or the ␣7X2 variant. The relative level of ␣7X1 and ␣7X2 is developmentally regulated. Similarly, the partner ␤1 integrin cytoplasmic domain is converted from the ␤1A to the ␤1D splice variant. To determine whether ␤1D modulates the activity of the ␣7 receptor, cells were transfected with ␣7X1 and ␤1D cDNA. ␣7X1 coupled with ␤1A failed to adhere to laminin-1, whereas cotransfectants expressing ␣7X1 and ␤1D showed strong adhesion. Interestingly, ␣7X1 complexed with ␤1A and ␤1D displayed the same level of poor adhesion to laminin-2/4 or strong adhesion to laminin-10/11. These findings indicate that ␣7 function is regulated not only by X1/X2 in its extracellular domain but also by ␤1 cytoplasmic splice variants. It is likely that expression of ␤1D alters ␣7X1 binding to laminin isoforms by a process related to ligand affinity modulation. Functional regulation of ␣7␤1 by developmentally regulated splicing events may be important during myogenic differentiation and repair because the integrin mediates adhesion, motility, and cell survival.