Wasps (20) 25
Tries: Sackey, Voyce, Lewsey Cons: Cipriani 2 Pens: Cipriani 2
Castres (3) 11
Try: Nallet Pens: McIntyre 2
Lewsey and Cipriani celebrated the third try with some shadow boxing
Tries from Paul Sackey, Tom Voyce and Josh Lewsey ensured Wasps opened their Heineken Cup campaign with a win.
Danny Cipriani also chipped in with 10 points from the boot with Wasps putting their early season misery behind them.
Wasps led 20-3 at the break with Cameron McIntyre adding the visitors' only points of the half.
Cipriani and Lewsey combined in the second half to put the game beyond doubt with French lock Lionel Nallet scoring a late try for Castres.
Sackey's opening try was a superb effort with Wasps quickly racing into a 17-0 lead.
Riki Flutey scooped up the loose ball and jabbed a grubber kick through for the England winger who collected the ball and side-stepped opposing winger Rafael Carballo in one move.
Sackey then fended off three Castres defenders to barrel over in the corner, an eighth-minute score which Cipriani successfully converted.
Soon after Voyce powered over for Wasps' second try of the game.
The left winger bounced off one tackle, spun clear and then weaved his way past three defenders to dive under the posts.
Castres' former Canterbury fly-half McIntyre kicked the visitors onto the scoreboard before they lost Darron Nell to the sin-bin.
Cipriani opened up a 20-3 half-time lead with a penalty before McIntrye added another three points early in the second period.
Cipriani then linked up with Lewsey, with whom he had a training round dust-up during the week, to push Wasps into a commanding position.
The England fly-half chipped forward and then stripped Castres full-back Thomas Bouquie of the ball before sending Lewsey clear down the right wing - and the pair then celebrated with a spot of good-humoured shadow boxing.
Late on Nallet plunged over for a Castres try but the conversion was missed and Wasps ensured they did not concede a losing bonus point.
Wasps coach Ian McGeechan:
"I thought it was a good defensive performance and offensively I thought we were very slick today.
"The experienced players had to take a lead and show up for real. I thought all of them did today. They delivered big time.
"It was obvious it meant a lot to everyone today. Honesty is what this club is about and I thought the honesty came out today.
"A lot of hard work went in and we got the benefits."
McGeechan on Cipriani and Lewsey:
"The problem is we need to stop them kissing each other at training as well.
"Danny needed 80 minutes. He is still coming back to form and match fitness. He did OK. He is getting there.
"I thought Josh was outstanding today. His carrying, his decision-making gave the forwards something to work off and it put us on the front foot."
Wasps: Staunton, Sackey, Lewsey, Flutey, Voyce, Cipriani, Reddan; Payne, Ibanez (capt), Vickery, Shaw, Palmer, Haskell, Rees, Worsley.
Replacements: Robinson for Reddan (59), Webber for Ibanez (59), Barnard for Vickery (67), Birkett for Shaw (63), Leo for Haskell (68), Betsen for Rees (74).
Not Used: Walder.
Sin Bin: Lewsey (62).
Castres: Bouquie, Mazars, Christophers, Sanchou, Carballo, McIntyre, Tillous Borde; Lensing, Terrain, Ducalcon, Capo Ortega, Nallet, Malonga, Nell, Faure.
Replacements: Bonnefond for Sanchou (46), Senio for Tillous-Borde (59), Forestier for Lensing (60), Giorgadze for Ducalcon (76), Capo for Gaston (54), Tomiki for Faure (63).
Not Used: Legardere.
Sin Bin: Nell (34).
Referee: Carlo Damasco (Italy)