The ability to assign a shared_ptr<T> to shared_ptr<const T> is useful for controlling which parts of software have write access to the shared object, so I'm surprised that while e.g boost::shared_ptr<int> sp(new int); boost::shared_ptr<const int> csp=sp; compiles fine, and prohibits e.g *csp=0;, the equivalent for shared_array doesn't compile: boost::shared_array<int> sa(new int[10]); boost::shared_array<const int> csa=sa; // not allowed [The gcc 4.1.2 error is "conversion from ‘boost::shared_array<int>’ to non-scalar type ‘boost::shared_array<const int>’ requested"] I'm looking to prevent modification of elements of csa of course. The obvious alternative is to use a shared_ptr to a std::vector of course: boost::shared_ptr<std::vector<int> > sv(new std::vector<int>(10)); boost::shared_ptr<const std::vector<int> > csv=sv; // fine // (*csv)[0]=0; // prevented by const, as intended However, it's unclear to me exactly why the shared_array of const doesn't work as expected. Am I missing some necessary detail to make it work, is shared_array simply less featureful (the header is certainly shorter) or is there some reason it can't work ? Thanks for any explanation Tim [I'm using boost 1.33.1]