Goals from Shane Long and Tom Ince saw Reading come from behind to claim a 2-1 victory at Cardiff.
Callum O'Dowda gave the home side the lead early on with a well-directed header but Long, making his first Royals start for 11 years, equalised from the penalty spot before the break.
Tom Ince, son of Reading manager Paul, made it 2-1 in the 63rd minute with a rasping effort from distance, and Cardiff were unable to mount a comeback.
The Bluebirds had been busy with their recruitment during the summer, with manager Steve Morison bringing in 14 new players. Eight of them started at the SCL Stadium.
Reading had made nine close-season signings and six of them were in their starting XI, with Ince Sr hoping for an improved display following last week's 1-0 defeat at Blackpool.
Cardiff, who opened their new campaign with a 1-0 home win over Norwich, began brightly and went ahead in the fourth minute.
Ryan Wintle swung over a free-kick from the right and O'Dowda - one of Cardiff's new signings - stooped to head in his first goal for the club.
Reading tried to regroup, without any success, and the visitors could have doubled their lead just before the quarter-hour mark after a quick break.
O'Dowda was left free in the area but although his effort was struck low and hard, goalkeeper Joe Lumley made a fine one-handed save.
It proved a costly miss, with the hosts equalising in the 27th minute. Tom Ince scampered through and, just as he was about to shoot, was pulled down by Curtis Nelson.
Referee Darren England pointed to the spot - and booked Nelson - with Long drilling home the penalty.
It was his first goal for the club since scoring twice at Cardiff in Reading's 3-0 victory in the second leg of their Championship play-off semi-final in May 2011.
Long moved to West Brom early the following season. Now 35, he re-signed for Reading after being released by Southampton this summer.
Though Reading went on to enjoy the better of the first half, it was Cardiff who almost regained their advantage early in the second half.
Substitute Joe Ralls curled a teasing free-kick into the area but the ball somehow evaded a cluster of bodies at the far post.
Reading responded positively and were rewarded when they went in front through Ince.
He collected a pass from Ovie Ejaria and fired home a superb 20-yard drive that appeared to catch Cardiff goalkeeper Ryan Allsop by surprise.
Sheyi Ojo shot wildly over as Cardiff looked for a leveller but Reading held on comfortably for their first win of the season.
What the managers said...
Reading's Paul Ince: "I'm delighted with the win today. It's probably an extension of the outstanding second half at Blackpool last week. I was disappointed at conceding the first goal. I'd told the lads that we needed to start fast and get the fans up.
"We gave a stupid free-kick away, didn't mark a man and, before you know it, we're 1-0 down. But this group of players, the core of it, just don't give in. The response was brilliant. We got the penalty we deserved and, in the second half, we performed really well. This team has got so much togetherness."
Cardiff's Steve Morison: "I'm disappointed, we didn't really turn up. It's just so frustrating. You drop your level and you lose games of football. I think it is a very even league this season. Anyone could beat anyone. This has just happened but we'll reflect on it over the weekend and go back and have a look at it. What's most frustrating for me was the attitude and mentality (of the players) rather than ability and what we did with the ball. We weren't brave enough and I don't think they had enough belief in themselves.
"Last week, we had all that stuff in abundance. But, at the end of the day, we're all human beings. They're allowed to have a bad day at the office. I just hope that those days are few and far between. We had a great start, we scored, and I thought it might have been the worst thing that could have happened. We had another chance, when Callum (O'Dowda) went through, but their keeper (Joe Lumley) has made a good save. It could have been 2-0 and we'd have been growing in confidence. But Reading go and score from a penalty and we then just gave them belief. Their second goal, obviously, was a screamer. But it was only because we gave them that confidence to go and do that."