I am a little confused about rgswoohoo comment. IMO, Fred Astaire and Arthur Murray both teach students to start on the 1 beat for all American dances, smooth and rhythm, except for mambo. In the example of the rumba, they differ on whether it is a SQQ or a QQS step pattern, but they both start on the 1 beat. Another difference, in Eastern Swing, AM starts with the back rock, FA starts with the first triple step, but again both start on the 1 beat. With their attempts to be "different", it has always amazed me that both studios start the Cha Cha with a left side step (for the man) on the 1 beat, and then a back step on 2. Since most studios in the US start beginning students on the American Style, the studios don't need to teach that International Latin Rumba starts on the 2 beat until the student has progressed, and hopefully can fathom the difference and not be confused (of course, there are a lot of other differences that the student must learn).