This paper presents simple, syntactic strong normalization proofs for the simply-typed λ-calculus and the polymorphic λ-calculus (system F) with the full set of logical connectives, and all the permutative reductions. The normalization proofs use translations of terms and types of λ →,∧,∨,⊥ to terms and types of λ→ and from F ∀,∃,→,∧,∨,⊥ to F ∀,→ . I didn't find a proof really nice, and taking little space [4, p. 130]. For instance, many proofs, like these in [7,9,10] are based on the computability method, or (in the polymorphic case) candidates of reducibility. This requires re-doing each time the same argument, but in a more complex way, due to the increased complexity of the language.We believe that methodologically the most adequate approach is by reducing the question of strong normalization of the extended systems to the known strong normalization of the base systems, involving only implication and the universal quantifier. We propose two such proofs in what follows.The first proof reduces the calculus λ →,∧,∨,⊥ with connectives ∧, ∨, →, ⊥ to the calculus λ → . Here we use the strong normalization of λ → with beta-etareductions. The proof is based on composing the ordinary reduction of classical connectives to implication and absurdity with Ong's translation of the λµ-calculus to the ordinary λη-calculus, as described e.g. in [8, Chapter 6]. To our knowledge this is the most direct way of showing SN for system λ →,∧,∨,⊥ .The above method does not however extend to the polymorphic case. Indeed, the translation is strictly type-driven and requires an a priori knowledge of all types a given expression can obtain by polymorphic instantiation. Also the well known definition of logical connectives in system F:is not adequate. The translation preserves beta-conversion, but not the permutations. The solution, first used by de Groote ([2], [3]), for first-order logic, is a CPS-translation. Our proof is similar to de Groote's but the version of CPS we use is based on Nakazawa and Tatsuta [6].