From Newsgroup: rec.arts.books.childrens

She lives in Eugene, Oregon.
Her birthday was on Nov. 24th.
http://www.sylviaengdahl.com/index.htm
I once got an email from her, years ago, asking how to track down her old illustrator, Ruth McCrea! (I hope she found her - McCrea died in Feb. 2016, aged 94. She was likely best known for illustrating the tiny cookbooks for the Peter Pauper Press.)
http://scholar.lib.vt.edu/ejournals/ALAN/fall97/littlejohn.html
(long analysis of her writing) http://images.google.com/images?hl=en&q=sylvia%20louise%20engdahl%20&um=1&ie=UTF-8&sa=N&tab=wi
(covers, photo)
https://duskpeterson.com/aslan/engdahl.htm
(about "interfaith fantasy") http://www.literature-map.com/sylvia+louise+engdahl.html
(what readers of Engdahl also like to read)
From an interview I can't find anymore:
"I prefer novels that focus less on adventure or 'far-out' concepts than on the feelings and moral dilemmas of the characters. And however great its literary quality may be, I have no patience with fiction that presents a pessimistic--and therefore, in my opinion, false--view of human progress or of humanity's place in the universe.")

https://www.youtube.com/watch?v=MkESShccFQ0
From Contemporary Authors:
Sylvia Louise Engdahl told CA that as a writer she aims to "bring present-day issues into perspective through speculation about the future as related to the past, with particular emphasis on space exploration, which I believe to be the most significant challenge facing the human race and the only long-range goal that will unite mankind in peace. . . . It is also my belief that today's tendency to equate realism with pessimism is invalid. My science fiction is not intended primarily for fans of that genre; rather, it is directed to readers without an SF background, and deals not so much with technological progress as with the human values I consider important.
"Because of the awards won by Enchantress of the Stars, I became known as an author for children; however, that is the only one of my novels intended for an audience below high school age. Unfortunately, the original editions of the others were generally placed next to it in the children's rooms of libraries, and thus often failed to reach the mature readers most apt to enjoy them. This was particularly true in the case of the second and third volumes of my trilogy, which has now been reissued as adult science fiction and is finally available in paperback."
WORKS
* Children of the Star (adult fiction omnibus edition; contains This Star Shall Abide, Beyond the Tomorrow Mountains, and The Doors of the Universe), Meisha Merlin (Atlanta, GA), 2000.
* Stewards of the Flame, (adult novel) 2007.
* Promise of the Flame, 2009.
* Defender of the Flame, 2013.
FICTION; FOR YOUNG ADULTS
* Enchantress from the Stars, illustrated by Rodney Shackell, Atheneum (New York, NY), 1970, new edition with jacket and vignettes by Leo and Diane Dillon, Walker (New York, NY), 2001.
* Journey between Worlds, illustrated by James and Ruth McCrea, Atheneum (New York, NY), 1970.
* The Far Side of Evil, illustrated by Richard Cuffari, Atheneum (New York, NY), 1971, revised edition, Walker (New York, NY), 2002.
* This Star Shall Abide (first novel in a trilogy), illustrated by Richard Cuffari, Atheneum (New York, NY), 1972, published as Heritage of the Star, Gollancz (London, England), 1973.
* Beyond the Tomorrow Mountains (second novel in trilogy), illustrated by Richard Cuffari, Atheneum (New York, NY), 1973.
* The Doors of the Universe (third novel in trilogy), Atheneum (New York, NY), 1981.
*
NONFICTION; FOR YOUNG ADULTS
* The Planet-girded Suns: Man's View of Other Solar Systems, illustrated by Richard Cuffari, Atheneum (New York, NY), 1974.
* (With Rick Roberson) The Subnuclear Zoo: New Discoveries in High-Energy Physics, Atheneum (New York, NY), 1977.
* (With Rick Roberson) Tool for Tomorrow: New Knowledge about Genes, Atheneum (New York, NY), 1979.
*
OTHER
* (Editor, with Rick Roberson) Universe Ahead: Stories of the Future (anthology), illustrated by Richard Cuffari, Atheneum (New York, NY), 1975.
* (Editor) Anywhere, Anywhen: Stories of Tomorrow (anthology), Atheneum (New York, NY), 1976.
* Our World Is Earth (picture book), illustrated by Don Sibley, Atheneum (New York, NY), 1979.
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