The temperature dependance of the proton NMR line shape, T-1 and T-1p of isotactic poly-1-butene forms I, I’, II, and III have been studied between 100 and 400 K (up to melting). The usual line shape decompositions concerning rigid vs. crystalline and mobile vs. amorphous phases are discussed. The rigid-lattice second moments were calculated introducing a fast rotation of the methyl group. Complex spin-lattice decays were analyzed as a continuous distribution of rates. Relax at ion behavior was analyzed in terms of a Williams-Watt correlation function. Motions in the crystalline parts of samples in forms II and III very similar to the amorphous one were revealed, leading us to compare form II to a condis crystal during the crystal form transformation.