My family has an anthem, a theme song we somehow fancied was unique to us. The song certainly seemed obscure enough--a rather unusual medley of "Over the Rainbow" and Louis Armstrong's "What a Wonderful World" sung by a now-dead Hawaiian music artist by the name of Israel Kamakawiwo'ole. (That's pronounced kah-MAH-kah-vee-vo-O-lay, but the singer was simply known as Iz.)

I came upon the song quite by accident while browsing at Borders one evening this spring. Digging through a bin of discount CDs that had been played on the store's sound system, I found a copy of Iz's 1993 album, "Facing Future." I bought it for two reasons--well, three if you count the fact that it was half-price: (1) My husband is from Hawaii and we like Hawaiian music, especially when we're feeling homesick; and (2) our older daughter, Rachel, then 4, was in the throes of a "Wizard of Oz" obsession. The idea of the childlike "Rainbow" crooned by a gigantic Hawaiian music star (Iz weighed more than 700 pounds) was irresistible.

So we took the CD home and played it for the kids. We expected to enjoy it; what we didn't expect was that all four of us would be so enchanted. The deceptively simple arrangement conveys a complexity of emotions; it manages to be both joyous and wistful, mellow and lively at the same time. The girls respond to its sweetness, their parents to its tenderness and hope.

The recording contains only Iz's strong, sweet, pure voice and his four-string ukulele. The melody is hummed and sung over a distinctly Hawaiian four- or five-chord pattern. The words aren't exact ("Somewhere over the rainbow, way up high, and the dreams that you dream of, once in a lullaby"), which adds to its charm. The tune has a light and captivating rhythm, and the track is five minutes long, which means it's just perfect for two often-weary parents of two live-wire children to dance to, though we sometimes play it over and over.

The medley became our "happy song," and we danced to it through spring, summer and into the fall, through good times, pouty moods, rainy days. It was one of our constants during the upheaval of a household move. The CD--which is uniformly excellent--pretty much lived in our rotating carousel, while other family favorites cycled in and out. More than once, I caught myself dancing to the medley entirely alone.

So imagine the shock, almost indignation, my husband and I felt one brisk evening when we were watching television and an advertisement for eToys--the Internet toy store--came on, featuring the signature strumming and "Over the Rainbow" humming that opens the piece. How, we wondered, had the online retailer found out about "our" song? More to the point, how had eToys come across a six-year-old recording by a dead Hawaiian artist whose music was barely known on the mainland?

After some investigating, I found out--this is always a blow--that my family isn't as unusual as we thought we were; in fact, the song was developing a minor cult following outside Hawaii long before we were lucky enough to find it. And it's partly because of the song that Iz is gaining national recognition after his death.

The song's first major mainland exposure came during a 1996 National Public Radio piece on the "gentle giant of Hawaiian song," during which host Noah Adams discussed it with a hip California deejay named Chris Douridas.

"You know, Chris," marveled Adams, "this has a sort of magical quality to it. I wonder if you thought about what makes it so compelling and so attractive?" Responds Douridas: "Well, there's something about the purity and honesty and simplicity of this that is so engaging, so emotionally charged."

Later he adds, "You know, the first time we played this, the phone just rang off the hook, and each and every time we play it, we get calls from the record company in Hawaii saying, 'What's going on? You guys must have played that song again.' "

NPR itself played the song again--when it reported Iz's death from respiratory failure in June 1997. He was 38 and at the height of his popularity in Hawaii.

In 1998, the song also appeared on a "Party of Five" episode and on the soundtrack of the movie "Meet Joe Black."

Surprisingly, the eToys people came to the song on their own, with a little bit of cosmic intervention. A copywriter at Publicis & Hal Riney, an ad agency in San Francisco, found the recording in a music store, and the agency had considered but rejected it for a different campaign. When the eToys ads were finished, the creative staff listened to more than 100 cuts, but none evoked the emotion it wanted for the spots.

Finally, someone remembered Israel's recording. They played it, and everyone just sat there "misty-eyed and melting," said producer Elissa Singstock. "We said, 'That's the piece, that's the one.' "

Says executive creative director John Doyle: "It just brings you back to childhood and the realization of how transient those years are, and that you should relish them while you can. When you think about your own children, it's always coupled with the knowledge that someday they're going to move on."

The song's genesis itself was kismet, according to Suzi Mechler, vice president of Mountain Apple Company, Iz's distributor. Apparently Iz called his sound engineer in the middle of the night and said, "I need to record something." (This gives new meaning to the fact that, in the "Wonderful World" portion of the medley, Iz sings "I like the dark" instead of "the dark sacred night"). When they were done, Mechler said, the engineer "knew he had magic" on the tape.

My family still dances to Iz's song, and somehow the idea of its universality, its increasing popularity, even its commercial appeal--the fact that it affects "Party of Five" fans, baby boomer parents, NPR hosts, ad agency execs and Hollywood directors the same way--can't really spoil it for us. We just think to ourselves, what a wonderful world.

(To hear a free Sound Bite of the medley, call Post-Haste at 202-334-9000 and press 8156.)