Positions where White has an isolated pawn on d4 (IQP) arise in many openings, including the Queen's Gambit Accepted; Nimzo-Indian; Caro-Kann Defense, Panov-Botvinnik Variation; and Alapin Sicilian. In the game below, the IQP occurred in a Smith-Morra Gambit Declined, which transposed into an Alapin Sicilian. If Black wants to decline the Smith-Morra Gambit, 3...d5 is not the most effective way to do so; Black ends up in an Alapin Sicilian where he has exchanged on d4 prematurely. I recommend either accepting the gambit or playing 3...Nf6. A lot of players are leery of taking on an IQP, fearing that it will be weak in an ending. However, as Tarrasch said, "Before the endgame, the gods have placed the middlegame." He also said, "He who fears an isolated queen's pawn should give up chess." The IQP supports a knight outpost on e5 and often results in a king-side attack for White. Another advantage of the IQP is that a sudden liquidation of the center with d5 is sometimes dangerous for Black, as seen in the game below. Although Black's opening moves were very plausible, 12.d5! already left him tactically busted in view of his loose pieces on c6 and b4, and the unfortunate vis-à-vis of Black's queen and White's rook on the d-file. Houdini 3 gives Black's best line as 12...Na5 13.dxe6 (unleashing a discovered attack on the queen) Qe7 14.exf7+ Kh8. After 12...exd5 13.Nxd5 Nxd5 14.Bxd5, White threatened both 15.Bxc6 and 15.Bxf7+, winning Black's queen. Black tried to defend everything with 14...Qc7, but I unleashed a whirlwind attack on his king with 15.Qe4! Bb7 16.Ng5! g6 17.Qh4!, forcing the ugly 17...h5. Houdini says that I should have continued with 18.Qe4! (threatening Qxg6+) Kh8 (even worse is 18...Kg7 19.Bxf7! Rxf7? 20.Ne6+, winning the queen) 19.Bf4! (not 19.Bxc6? Qxc6! 20.Qxb4?? Qxg2#) Qe7 20.Bxc6, winning a piece. My 18.Bf4?! was less accurate, when Black could have played on with 18...Qe7. After 18...Bd6??, Black resigned before I could play 19.Bxd6 Qxd6 20.Bxf7+! Rxf7 21.Rxd6.