GRET detection threshold, thus giving the appearance that BL Lac objects as a class experience less dramatic and less frequent $\gamma$-ray flares. The general properties of the low frequency outbursts of BL Lac objects, however, would be very similar to that of the FSRQs.

In order to achieve a better understanding of the emission mechanisms of $\gamma$-rays from blazars a study of the correlated short time scale ($\sim 1-3$ days) $\gamma$-ray variations with those at other frequency bands is needed. Since the predictions of time delays between the flux changes at various frequencies are different for the individual models for both the seed photons and the nature of the inner jet, this method could provide a means to discriminate between the different models. The differences in the model predictions are discussed in more detail by Marscher et al. (1995). Gamma-ray variability in the different models may have different impacts on the spectral behavior during the build-up and decline of an outburst. Studying the short-time-scale behavior and looking for spectral changes while following a complete outburst may be the key to pin down the basic emission mechanisms.

Summary
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In conclusion, the EGRET results have shown the importance of the $\gamma$-ray window on blazars. The high luminosities and strong time variability observed have pushed theoretical models to emphasize relativistic jets of particles seen at small angles to the line of sight. The EGRET observations have established that the $\gamma$-ray window is critical for understanding the properties of blazars. Future observations with CGRO and successor $\gamma$-ray observatories like INTEGRAL and GLAST should play a key role in resolving the physics of these powerful sources.

The author presents this work on behalf of the EGRET Team and acknowledges contributions from D. L. Bertsch, S. D. Bloom, B. L. Dingus, J. A. Esposito, C. E. Fichtel, R. C. Hartman, S. D. Hunter, G. Kanbach, D. A. Kniffen, Y. C. Lin, H. A. Mayer-Hasselwander, L. M. McDonald, P.