Titulo: An Operational Characterization of (Lazy)-Strong Normalization Abstract: The standard lambda-calculus equipped with the beta-reduction is the language for the call-by-name functional computation. Its call-by-value version is the well known Plotkin's lambda-Bv-calculus. In this work, we use the parametric lambda-Delta-calculus in order to present a logical characterization of lazy strongly beta-normalizing terms using intersection types. This characterization, besides being interesting by itself, allows an interesting connection between call-by-name and call-by-value lambda-calculus. In fact, it turns out that the class of lazy strongly beta-normalizing terms coincides with that of call-by-value potentially valuable terms. This last class is of particular interest since it is a key notion for characterizing solvability in the call-by-value setting. We also introduce the Phi-calculus, a new call-by-value version of the lambda-calculus. The Phi-calculus satisfies some interesting properties, in particular that its set of solvable terms coincides with the set of beta-strongly normalizing terms in the classical lambda-calculus.