The prisons differed structurally and in classification of inmates--two were medium- and two were high-security prisons. The study examined the type of weapons used in relation to the propensity for and frequency of noncollective (inmate-to-inmate and inmate-to-staff) violent incidents at the two types of prisons. The results indicated that the scope and nature of assault varies greatly from prison to prison mostly as a result of freedom of movement to make weapons and the security classification of the inmates housed. Figures and four references are supplied. (Author abstract modified)