I am neither Bipolar II nor an expert; but it sort of seems to me that if a hypomanic episode had *not* been involved, there wouldn't be a "high" to contrast the "low," and so it wouldn't fall under a bipolar category. Without the evidence of hypomania, rapid cycling, and so forth; it doesn't seem to me that it would differ a whole lot from Major Depression. *Something* has to make it bipolar, after all.

Bipolar II seems to differ from Bipolar I in that it specifically must *not* have included a major manic episode. I, being Bipolar I, have had a huge first-time manic episode in which I was basically out of my mind for a good four or five months. This took place in the year 2004. So I'm definitely not Bipolar II, but I can see from the set of symptoms cited in the DSM-IV that to be Bipolar II, one must have at least some hypomania in one's experience.