For large systems, the determination of the entire quantum state is no longer possible in practice and one is interested in methods that determine only a subset of the parameters necessary to characterize the quantum state that still contains important information about the state. Permutationally invariant quantum tomography is such a method. PI quantum tomography only measures ϱ ϱ P I , the permutationally invariant part of the density matrix. For the procedure, it is sufficient to carry out local measurements on the subsystems. If the state is close to being permutationally invariant, which is the case in many practical situations, then ϱ ϱ P I is close to the density matrix of the system. Even if the state is not permutationally invariant, ϱ ϱ P I can still be used for entanglement detection and computing relevant operator expectations values. Thus, the procedure does not assume the permutationally invariance of the quantum state. The number of independent real parameters of ϱ ϱ P I for N qubits scales as ∼ ∼ N 3 . The number of local measurement settings scales as ∼ ∼ N 2 . Thus, permutationally invariant quantum tomography is considered manageable even for large N . In other words, permutationally invariant quantum tomography is considered scalable.