We present data on the transport of charge carriers in the organic semiconductor tetracene. Comparative measurements by time-of-flight (TOF) spectroscopy and measurements in field-effect transistor (FET) geometry reveal hole mobilities of about 1 cm2/Vs. Whereas for FETs only hole transport can be detected, from TOF a strong dispersive transport for negative charge carriers is observed. This observation is mainly caused by deep-level trapping of electrons. By fitting the temperature dependent hole mobility to a model of multiple-trapping and release of charge carriers the trap energy and the relative trap density can be adjusted to 130 meV and 5·10-3, respectively. Comparative chemical and structural analysis of inhomogeneities show that the traps affecting the transport are mainly caused by chemical defects rather than by structural imperfections.