There exist an increasing number of studies that demonstrate the necessity to evaluate the processes which characterize a program and guarantee its implementation and evaluation. This paper deals with the implementation of a program designed to improve the acculturation of immigrant families in Spain (EU). Implementation followed a process that has proved successful in other settings, but is being applied here for the first time. Qualitative and quantitative measures are employed to assess each stage of implementation, with a particular emphasis on fidelity to program design. The intent was to guide effective revision of the program, and to establish it in a form that can be implemented on a larger scale. (Contains 5 tables and 1 figure.)