[en] In this paper it is examined the possibility of generating squeezed states out of coherent states by external changes of the oscillator mass and frequency. Using the evolution operator method developed by Cheng et al., it is investigated the evolution of a coherent state of a time-dependent oscillator with variable mass and frequency as well as its squeezing and coherence property. Our analyses indicate that the wave function of the time-dependent oscillator starts as a coherent state at t = 0 and evolves as a squeezed state at a later time