Even though in-house development and the use of application packages form two major strategies for developing information systems, there is practically no research into the comparative implementability of information systems developed according to these strategies. The paper suggests that the level of originality of information systems can be used as a theoretical concept underlying the dichotomy of in-house development vs. application packages, and puts forward a set of hypotheses regarding the influence of the level of originality on the implementability of information systems. The hypotheses form the theoretical basis for a comparison of the two types of information system development in terms of implementability, and clearly support Lynch's finding (Lynch, 1984) that the implementation of application packages is more difficult than one might initially expect.