  The construction of Generalized Intelligent States (GIS) for the $x^4$%
-anharmonic oscillator is presented. These GIS families are required to
minimize the Robertson-Schr\"odinger uncertainty relation. As a particular
case, we will get the so-called Gazeau-Klauder coherent states. The properties
of the latters are discussed in detail. Analytical representation is also
considered and its advantage is shown in obtaining the GIS in an analytical
way. Further extensions are finally proposed.
