Presented here are theorems concerning upper semicontinuous decompositions of developable spaces, topological in the sense that the common parts of intersecting domains (open sets) are open. Theorem 1 shows that, if the elements of such a decomposition do not have nonbicompact [I] intersections with the closures of their complements, the decomposition space is developable. Theorem 2 shows that if additionally the space covered by the decomposition is complete in a certain Cauchy sense defined below the decomposition space is complete in this sense. Theorem 3 is a variation of Theorem 2 dealing with a nonequivalent [10] Ascoli type completeness property. Under Consequences some implications of Theorems 1 and 2 are given. One of these gives affirmative resolutions of the following questions raised by R. L. Moore: (1) Do upper semicontinuous decompositions into compact point sets of spaces satisfying Axiom 0 and Axiom 13 (the first three conditions of A xiom 1) of "Foundations of point set theory" [6] yield spaces satisfying these axioms? (2) Do such decompositions of spaces satisfying Axiom 1 yield spaces satisfying this axiom? Two other consequences are theorems of Morita-Hanai-Stone [7], [12 ] and I. A. Valnsteln [13]. The sequence G1, G2, G3, * is said to be a development of the space 2 provided that (1) for each n, Gn is a collection of domains covering z and (2) if P is a point and D is a domain containing P, then for some n every element of Gn containing P is a subset of D. A space is said to be developable provided it has a development [2]. The developable space z is said to be complete in sense C or sense A accordingly as it has a decreasingly monotonic development G1, G2, G3, * * * satisfying the first or second of the following conditions: Condition C. If J is an infinite point set and for each n some gn of Gn contains all except finitely many points of J, then there exists a point P such that every domain containing P contains infinitely many