This report is based upon information obtained from personal interviews with a representative sample of Puerto Rican adults, both patients and non-patients, 20 years of age and over, living in two urban communities in central Connecticut, with 1,000 and 8,000 Spanish-speaking residents, respectively. The findings of this research are summarized as follows: the informants, whether patients or normal members of the community, differ very little in their conception of mental illness; they distinguish two broad categories of mental illness "craziness", similar to psychotic behavior, and "nervousness" or "bad nerves", which could be categorized as psychosomatic or neurotic conditions; for both types of conditions there is believed to be a range of causative factors, supernatural or natural: among the natural causes there are three major types - bilogical (e.g. alcohol, drug abuse, sexual excess, and malnutrition); psychological (e.g. excessive emotional suffering and excessive physical punishment in childhood); and social (e.g. working too hard and poverty); spiritualism, witchcraft and fate are believed to be the most important supernatural causes of mental illness; and, the latter become most clearly apparent as factors of importance when informants are asked about them in such a way that they are not obliged to speak directly about their own personal beliefs. (Author/JM)