1590s, from well (adv.) + past participle of behave (v.).
Entries linking to well-behaved
well adv.
"in a satisfactory manner," Old English wel "abundantly, very, very much; indeed, to be sure; with good reason; nearly, for the most part," from Proto-Germanic *wel- (source also of Old Saxon wela, Old Norse vel, Old Frisian wel, Dutch wel, Old High German wela, German wohl, Gothic waila "well"), from PIE root *wel- (2) "to wish, will" (source also of Sanskrit prati varam "at will," Old Church Slavonic vole "well," Welsh gwell "better," Latin velle "to wish, will," Old English willan "to wish;" see will (v.)).
Also used in Old English as an interjection and an expression of surprise. The adjective was in Old English in the sense "in good fortune, happy," from the adverb; sense of "satisfactory" is from late 14c.; "agreeable to wish or desire" is from mid-15c.; "in good health, not ailing" is from 1550s. Well-to-do "prosperous" is recorded by 1794.
behave v.
early 15c., reflexive, "conduct or comport" (oneself, in a specified manner), from be- intensive prefix + have in sense of "to have or bear (oneself) in a particular way, comport" (compare German sich behaben, French se porter). The cognate Old English compound behabban meant "to contain," and alternatively the modern sense of behave might have evolved from behabban via a notion of "self-restraint." In early modern English it also could be transitive, "to govern, manage, conduct." Related: Behaved; behaving.