  We present the detection of kinematic infall signatures towards the Class 0
protostellar system SMM4 in the Serpens cloud core. We have observed the dense
molecular gas towards the embedded source using millimeter and submillimeter
line transitions of density sensitive molecular tracers. High signal-to-noise
ratio maps obtained in HCO+ J=1-0, J=3-2, and J=4-3, and CS J=2-1 show the
blue-bulge infall signature. The blue-bulge infall signature can be observed in
the centroid velocity maps of protostellar objects when infall dominates over
rotation. The line profiles of HCO+ and CS exhibit the characteristic blue
asymmetric line profile signature consistent with infall. In addition, HCO+ and
CS optical depth profiles obtained using isotopic observations show a red
asymmetry also consistent with an infall interpretation. Using
three-dimensional radiative transfer models based on the rotating, collapse
model of Terebey, Shu and Cassen, we derive infall parameters of the source. To
determine the direction and orientation of molecular outflows in the larger
Serpens cluster, wide-field mapping of CO J=1-0 emission was also performed.
