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The Philadelphia structural block in the Piedmont of Pennsylvania is dissected by a network of Paleozoic shear zones that cross-cut Taconic metamorphic zones and structures. The Wissahickon Formation (pelitic and semipelitic schist) was intruded by the Springfield granodioritic pluton, and the northern margin of the pluton was later intensely sheared in a northwest-dipping mylonite zone (here named the Llanerch thrust zone). Kinematic analysis revealed oblique reverse displacement in a due south direction on the Llanerch thrust. The direction of thrusting is parallel to the Crum Creek shear zone that is the boundary of the Springfield pluton on the western margin where the thrust is intersected. Sinistral offset of metamorphic zones in the Wissahickon Formation approximately 3-4.5 km occurs across the Crum Creek shear zone. The mapped width of the kyanite zones is relatively uniform along strike within the Wissahickon Formation of the hanging wall block north of the Llanerch thrust zone. The first sillimanite zone is very narrow due to truncation along the thrust; the second sillimanite zone lies in the footwall. Based on the structural thickness of the metamorphic zones, the heave on the Llanerch thrust is calculated to be a minimum of 1.5 km. Development of the Llanerch thrust was largely controlled by horizontal movement of the wedge of rock between the Rosemont zone and the Springfield pluton, causing part of the Wissahickon Formation to be thrust over toward the south. Parallel movement direction of the transcurrent Crum Creek zone and the Llanerch thrust suggests the structures are cogenetic. If this is the case, the amount of displacement across the southern segment of the Crum Creek zone must be 1.5 km greater than displacement across the northern segment of the zone to account for the contractional deformation on the Llanerch thrust wedge. Using metamorphic zones in the Wissahickon Formation, a complex palinspastic reconstruction of the postTaconic shear zones places the Wilmington Complex (root of the Taconic magmatic arc) directly adjacent to the West Chester massif (Laurentian Grenville basement) sometime during the middle to late Paleozoic.