PA 329 begins at an intersection with PA 873 in the community of Neffs in North Whitehall Township, Lehigh County. From this intersection, the route heads southeast on two-lane undivided Bellview Road past housing developments, soon passing under I-476 (Pennsylvania Turnpike Northeast Extension). After this, the road curves east into agricultural areas with a few homes, with PA 329 making a turn southeast onto Old Post Road. The route makes a curve to the east again as it continues through more farmland with scattered residential subdivisions. Upon entering Whitehall Township, the road becomes Main Street and passes through the residential community of Egypt before continuing past more homes and reaching the PA 145 junction. From this point, PA 329 continues northeast through residential areas and passes through the community of Cementon.
Upon crossing the Lehigh River, PA 329 enters Northampton in Northampton County and becomes 21st Street, crossing a Norfolk Southern railroad line as it heads into commercial areas. After crossing Main Street, the route is lined with homes before it crosses the Hokendaqua Creek into Allen Township and continues east. At this point, the name of the road becomes Nor Bath Boulevard and it passes between a quarry and a lake to the north and industrial areas to the south before entering farmland. PA 329 briefly passes homes after the Howertown Road junction, crossing into East Allen Township at the Seemsville Road intersection. The route continues through agricultural areas with some housing before reaching the PA 987 junction. At this point, PA 987 forms a concurrency with PA 329, with the two routes continuing east before turning northeast and passing to the east of a quarry. The road passes near a cement plant before it heads into Bath. Here, the road becomes Race Street and passes through woods before heading into residential areas. PA 329 reaches its eastern terminus at the PA 248 intersection, where PA 987 makes a turn east to follow PA 248.