When was it recorded? Feb. 19 and Mar. 30, 1965
When was it first released, and on which album? Aug. 6, 1965 on “Help!”
Who wrote it? Lennon/McCartney
Have I heard this song before? No
What my research dug up:
John and Paul wrote “You’re Going to Lose That Girl” at John’s home in Weybridge. According to the Beatles Bible, “The lyrics… are quintessential early Lennon, warning an unidentified male of his predatory intentions towards his female lover.”
The Beatles recorded the tune Feb. 19, 1965, three days before heading to the Bahamas to film part of “Help!” They recorded two takes of the rhythm track but only completed the second take, which was used.
They then added overdubs that don’t matter because they were quickly wiped. John, Paul and George then recorded more vocals.
On Mar. 30, 1965, George overdubbed a new lead guitar part, Paul overdubbed a piano part, and Ringo added a bongo part. The violà, the song was complete. Fun fact – the song was credited as “You’re Gonna Lose That Girl” on the US release of “Help!”
Naturally, “You’re Going to Lose That Girl” appeared in the film “Help!” The scene was filmed at Twickenham Studios, where the Beatles later filmed their documentary “Let It Be.” Quoth Alan Pollack, “The scene, for all its absurd, staged surreality… provides a delightful fantasy of what the real recording sessions might have been like.” (Spelling and Grammar tells me “surreality” is not a word, but it definitely should be.)
*12/12/14 — I’m having trouble getting the movie clip embedded (it worked fine the other night when I made this post, I swear!). The link isn’t working either when I paste it in here, so I’m going to let this page sit for a bit before trying again. Sorry!
Sources
http://en.wikipedia.org/wiki/You%27re_Going_to_Lose_That_Girl
http://www.icce.rug.nl/~soundscapes/DATABASES/AWP/ygtltg.shtml
and the band begins to play 
One of my all time favorite songs. The backing vocal lines are brilliant. The song is so well crafted. It’s a hidden gem i think. Thanks for posting it.
I had never heard this one before, so I definitely agree on the “hidden gem” part! Thanks for commenting. 🙂
I love this song! Ever since I first heard (and watched) it in ‘Help!’ a bit over a year ago, there is something magical about it that I can’t quite put my finger on. The scene in ‘Help!’ would be my favourite part in the film along with the scene in the Alps. ( And yes, ‘surreality’ should totally be a word!)
You know, I’m not sure I’ve actually seen “Help!” I’ve seen plenty of the scenes while doing this blog, but I’ll have to sit down and watch it one of these days. It looks so wonderfully absurd (which, based on “A Hard Day’s Night” and the Beatles’ demeanor in general is probably a good guess)! Thanks for commenting. 🙂
Help!’s my favourite Beatles film. It’s awesome! You’ll want the flat that the band lives in after watching it…