In this paper, noncoherent sequence detection (NSD) proposed Colavolpe and Raheli (see Proc. IEEE Int. Conf. Commun. (ICC '97), Montreal, p.21-5, 1997, IEEE Commun. Lett., 1998, and Proc. IEEE Intern. Conf. Commun. (ICC '98), Atlanta, GA, USA, p.438-43, 1998) is extended to continuous phase modulation (CPM). CPM is treated here jointly with linear modulations with intersymbol interference (ISI) since it is mathematically equivalent to a sum of ISI-affected linearly modulated components, according to Laurent (1986) representation. We first consider combined noncoherent sequence detection and decoding of coded linear modulations in the presence of ISI. The results we then extended to the case of M-ary CPM signals. The proposed sub-optimal detection schemes have a performance which approaches that of coherent detection with an affordable level of complexity. The robustness of noncoherent sequence detection schemes to phase noise is also demonstrated.