Brack could not match De Ferran's pace
The 33-year-old Brazilian set a best lap of 59.421 seconds in his Team Penske Reynard-Honda to put himself a remarkable half a second clear of the field.
De Ferran, who lay second in the championship six points behind the points leader Kenny Brack going into this race, will be joined on the front row by Bruno Junqueira with Brack third.
De Ferran's Penske team-mate Helio Castroneves was fourth.
'Vital'
De Ferran, who secured a championship point for pole position, said: "We had a successful day for two reasons.
"First, we gave ourselves an advantage by qualifying on the pole.
"Starting up front is always important on a tight street circuit like this where it is difficult to pass.
"Second, we earned a point towards the championship, and every single point is extremely important given the tight battle."
Qualifying for Sunday's Texaco/Havoline Grand Prix from the 2.457-kilometre (1.527-mile) Houston street circuit:
1 Gil de Ferran (Bra) Reynard-Honda 59.421 seconds,
148.853 kph (92.513 mph)
2 Bruno Junqueira (Bra) Lola-Toyota 59.943
3 Kenny Brack (Swe) Lola-Ford 59.947
4 Helio Castroneves (Bra) Reynard-Honda 60.063
5 Alex Tagliani (Can) Reynard-Ford 60.191
6 Dario Franchitti Reynard-Honda 60.433
7 Scott Dixon (NZ) Reynard-Toyota 60.446
8 Cristiano da Matta (Bra) Lola-Toyota 60.491
9 Mauricio Gugelmin (Bra) Reynard-Toyota 60.502
10 Tony Kanaan (Bra)Reynard-Honda 60.548
11 Roberto Moreno (Bra) Reynard-Toyota 60.612
12 Michael Andretti (USA) Reynard-Honda 60.625
13 Christian Fittipaldi (Bra) Lola-Toyota 60.681
14 Tora Takagi (Jap Reynard-Toyota 60.793
15 Adrian Fernandez (Mex) Reynard-Honda 60.861
16 Shinji Nakano (Jap) Reynard-Honda 60.949
17 Oriol Servia (Spa) Lola-Ford 61.182
18 Michel Jourdain Jr (Mex) Lola-Ford 61.192
19 Max Papis (Ita) Lola-Ford 61.289
20 Patrick Carpentier (Can) Reynard-Ford 61.310
21 Paul Tracy (Can) Reynard-Honda 61.382
22 Bryan Herta (USA) Reynard-Ford 61.418
23 Memo Gidley (USA) Lola-Toyota 61.611
24 Jimmy Vasser (USA) Reynard-Toyota 62.129
25 Casey Mears (USA) Reynard-Honda 62.799
26 Max Wilson (Bra) Lola-Ford 62.912.