Westudy slowlight dynamics inRbvaporcell. Wepresent datashowing significant pulse reshaping whenthebandwidth ofthepulses isincreased. We present a modelthat qualitatively explains theobserved behavior. C2005Optical Society ofAmerica OCIScodes: (270.1670) Coherent optical effects, (270.5530) Pulse propagation andsolitons