We analyze reducibility points of representations of p-adic groups of classical type, induced from generic supercuspidal representations of maximal Levi subgroups, both on and off the unitary axis. We are able to give general, uniform results in terms of local functorial transfers of the generic representations of the groups we consider. The existence of the local transfers follows from global generic transfers that were established earlier.wherewhere X(M) F is the group of the F -rational characters of M, χ ∈ X(M) F and ·, · is the pairing between X(M) F and a. The aim of this paper is to determine the reducibility points for I(s α, τ ) for all s ∈ C, whenever τ is generic, i.e., it has a Whittaker model, in the setting of a pair (G, M) of classical type, in terms of functoriality as we now explain.By assumption M = GL(m) × G(n) and in each case L G embeds into GL(N, C) × W F for a minimal N, with an image with a classical derived group (cf. (2.3) for more detail). Write τ = σ ⊗ π. By local transfer, π transfers to Π = Π 1 ⊞ · · · ⊞ Π d on GL(N, F ) (Theorem 3.2 here, [7,12,13,30,31]).Our main tool is to consider the poles of the intertwining operators (thus zeros of Plancherel measures), as proposed by Harish-Chandra [19,46], which we determine through poles of certain L-functions [39] (Theorem 2.13 and Corollary 2.14 here). Local transfer allows us to show that these poles exist only when σ is quasi-self-dual (conjugate-self-dual when G(n) is unitary) and σ is of the opposite type to the L-group of G (i.e., orthogonal versus symplectic, see Section 4) or σ is among the Π i when it is of the same type as the L-group of G.This provides us with complete information about reducibility points on the unitary axis for all groups of classical type. The reducibility off the unitary axis follows from [39, Theorem 8.1] (Theorem 4.24 here). These results are stated as Theorem 4.12 and summarized for individual groups as Propositions 4.26 -4.31.The case of induction from other discrete series representation of M must also be addressed and it is left for the future. One should also verify the equality of the arithmetic R-groups, defined by Langlands and Arthur [1, §7], with the analytic R-groups, defined by Knapp and Stein [8], as conjectured by Langlands and Arthur.The poles of intertwining operators can also be determined by direct calculations and there is a large body of work on this topic, starting with [42,43,16,17,18] and ending with some recent work [45,48,34,10], where the connection to functoriality is fully established in some rather general cases (SO(2n + 1, F )).The theory developed in [39] (Theorem 4.24 here) applies to any quasi-split group and in [33], Jing Feng Lau has determined the complete reducibility results for exceptional groups E 6 , E 7 , and E 8 , where M der is a product of three SL-groups, using poles of triple product L-functions which are of Artin type [32]. The case of exceptional group G 2 was fully treated in [39] This paper is organized as follows. In Section 2 we introduce our notation a...