Proton beam stability under collision with high current electron bunches was of foremost concern during the design stages of the HERA electron-proton collider. In initial commissioning the beam-beam interaction proved to be a key factor in determining the lifetime of the proton beam. But with appropriate measures proton beam lifetimes of hundreds of hours are routinely observed. Also for the electron and positron beams the beam-beam force can easily limit the lifetime and it can diminish the beam's polarization. Both effects have been shown in experiments. While new low-beta insertions, which are currently being commissioned, have been installed for the detectors H1 and ZEUS, the beam-beam force has increased. Several experiments have been performed before and after this luminosity upgrade to estimate the influence of the increased beam-beam effects and a comparison with computations shows that these effects can be accurately simulated.


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