After examining how Council of Europe member States deal with overcrowding in penal institutions, the article concludes that the two major ways of combating overcrowding are to build more prisons or reduce the number of prisoners. The member States tend to deal with overcrowding by making new places available in prisons, by finding alternatives to short custodial sentences or pretrial detention, and by finding alternatives to long custodial sentences. As the article further observes, giving priority to the construction of additional cells tackles the effects of overcrowding. However, recurrence of the problem can be prevented only by addressing its causes. In addition, solving short custodial sentences tackles sentences which have the least effect on prison populations. The longer the sentence the greater the burden on the penal system and the greater the urgency to deal with the problem. Notes, figures, table, bibliography