  We summarize the signals at HERA in supersymmetric models with explicitly
broken R-parity. As the most promising case, we consider in detail the resonant
production of single squarks through an operator $L_1Q_i{ \bar D}_j$, a
production process analogous to that for leptoquarks. However, the dominant
decay of the squark to a quark and a photino leads to a very different
experimental signature. We examine in particular the case where the photino
decays to a positron and two quarks. Using a detailed Monte-Carlo procedure we
obtain a discovery limit in the squark mass---Yukawa coupling plane. HERA can
discover a squark for a mass as large as $270 \gev$ and for an R-parity
violating Yukawa coupling as small as $5.8 \times 10^{-3}$.
