Intense sibling loyalty was examined in three sibling groups: (1) four brothers in mid-life, aged 36-45, three of whom were married; (2) two brothers, aged 20 and 22, attending the same university; and (3) a brother age 6 and his sister age 9 living together in a foster home. Anecdotal excerpts from extensive videotaped interviews are used to illustrate what sibling solidarity is and how it is demonstrated, to show how such strong attachments are formed, and to identify the benefits and burdens of such loyalty. (JMB)