[en] Investigations of diffractive interactions using data taken in 1994 with the H1 detector at HERA are presented, in the form of the contributions to the international workshop on deep-inelastic scattering and related phenomena, Rome, April 1996. This report covers inclusive measurements of diffraction both in deep-inelastic scattering and in photoproduction, energy flow and open charm production in diffractive deep-inelastic scattering, jet studies at all Q², a thrust analysis of diffractive deep-inelastic scattering and photoproduction and electroproduction of vector mesons. (orig.)