The paper studies Σ 0 n -computable families (n ⩾ 2) and their numberings. It is proved that any non-trivial Σ 0 n -computable family has a complete with respect to any of its elements Σ 0 n -computable non-principal numbering. It is established that if a Σ 0 n -computable family is not principal, then any of its Σ 0 n -computable numberings has a minimal cover and, if the family is infinite, is incomparable with one of its minimal Σ 0 n -computable numberings. It is also shown that for any Σ 0 ncomputable numbering ν of a Σ 0 n -computable non-principal family there exists its Σ 0 n -computable numbering that is incomparable with ν. If a non-trivial Σ 0 ncomputable family contains the least and greatest elements under inclusion, then for any of its Σ 0 n -computable non-principal non-least numberings ν there exists a Σ 0 n -computable numbering of the family incomparable with ν. In particular, this is true for the family of all Σ 0 n -sets and for the families consisting of two inclusion-comparable Σ 0 n -sets (semilattices of the Σ 0 n -computable numberings of such families are isomorphic to the semilattice of m-degrees of Σ 0 n -sets).