  The objective of this Ph.D. thesis is the implementation of the Worldline
Formalism in the frame of Noncommutative Quantum Field Theories. The result is
a master formula for the 1-loop effective action that is applied to a number of
scalar models -- among them the Grosse-Wulkenhaar model. As a byproduct we find
an expression for the small propertime expansion of general nonlocal operators'
Heat Kernel. As an introduction, basic notions of spectral functions, Quantum
Field Theories --path integrals and renormalization by means of spectral
functions-- and the Worldline Formalism for commutative theories are given.
