LEON Barnett kept Albion in the automatic promotion places with a priceless 49th-minute equaliser.
The Baggies bossed this top-of-the-table clash for long spells but fell behind from another set-piece after just six minutes when centre-half Leigh Bromby swept home his first Hornets goal.
Recalled defender Barnett denied away-specialists Watford an 11th win on their travels by heading home his third goal of the season from Zoltan Gera's free-kick.
The Baggies went on to create numerous chances and sub Roman Bednar had a goal wrongly disallowed for offside - but they couldn't break through Watford's stubborn resistance a second time.
The draw lifted Albion above Bristol City into second place on goal difference and extended their Championship run to just one defeat in nine games.
Albion started the game in third place after Stoke's win at Coventry and Bristol City's goalless draw with Wolves moved them above the Baggies into the automatic promotion places.
Tony Mowbray rang four changes, with top scorer Kevin Phillips, James Morrison, Gera and Barnett coming in for Luke Moore, Chris Brunt, Pele and the injured Martin Albrechtsen.
Former Baggies striker Nathan Ellington started on the Watford bench.
The sell-out home crowd pumped up the volume from the first whistle and Albion created the first chance after only two minutes when Gera lost marker Jordan Stewart to head Jonathan Greening's free-kick wide from 12 yards.
The Baggies had started brightly - but found themselves behind in the sixth minute.
Dean Kiely did well to block John-Joe O'Toole's six-yard header from Jobi McAnuff's corner but the rebound fell perfectly for Bromby who swept home from close range.
Albion were soon back on the attack but Gera failed to trouble Hornets keeper Richard Lee with an ambitious 30-yard drive.
In the 17th minute, ex-Hornet Paul Robinson floated a wonderful ball over Watford right-back Lloyd Doyley to put Morrison clean through.
The former Middlesbrough midfielder beat the onrushing Lee to the ball but saw his attempted lob brilliantly blocked by the Hornets keeper.
Albion were keeping Aidy Boothroyd's boys pegged inside their own half and Stewart came to his team's rescue when he deflected over Greening's fierce drive from just inside the box.
The hosts were enjoying plenty of possession but were struggling to break down Watford's red defensive wall and had to resort to long-range efforts.
Neil Clement was the next to try his luck, sending a 30-yard piledriver just over.
Lee then comfortably collected a dipping Phillips shot from similar distance before Albion's top scorer curled a 20-yard free-kick just over.
Albion almost broke through in the 36th minute when a John Eustace error gifted Ishmael Miller the ball just outside the visitors' penalty area.
However, Danny Shittu denied the former Manchester City striker a clear run on goal with a perfectly-timed last-ditch tackle.
Watford had barely threatened since taking the lead but twice went close in the 38th minute.
Kiely had to pull off a wonderful one-handed save to keep out Tamas Priskin's header from McAnuff's free-kick.
Two corners later, Kiely could only punch Stewart's flag-kick to the unmarked Bromby who wastefully fired over from 15 yards.
Albion went agonisingly close to drawing level in the final minute of the half when Clement smashed a 20-yard free-kick against the bar.
There was still time for more drama at the other end when Priskin did brilliantly to hold off Robinson and Clement and backheel the ball to Tommy Smith, who found McAnuff in the box.
The lively winger twisted and turned before firing over from 15 yards.
Albion started the second half like a house on fire and were level in the 49th minute.
Barnett lost marker Shittu to head Gera's perfectly-flighted free-kick home from six yards.
Back came Watford and Robinson risked life and limb when he threw himself in the way of Darius Henderson's close-range shot to divert it away from danger.
The game was now being played at a frenetic pace and, after Miller had spearheaded a swift Baggies breakaway, Phillips failed to get enough power on his header to beat Lee from Robert Koren's centre.
Albion were firmly back on the front foot and Lee had to be alert to push away Miller's cross-cum-shot after the Baggies striker had powered past Bromby.
Watford failed to clear the resulting corner but Barnett, who had become a real threat in the opposition box, could only nod wide after Gera had headed Morrison's deep centre back into the danger-zone.
Albion created a glorious chance in the 66th minute when Phillips' delightful dink put Miller in the clear in the box.
Lee rushed off his line to block the powerhouse striker's prod goalwards and the Watford keeper then did brilliantly to bounce back onto his feet and push away Morrison's follow-up.
Mowbray made his first change a minute later, replacing Morrison with Brunt, and performed his second in the 73rd minute, with Bednar coming on for Miller.
Albion were still doing all the pressing and Gera wasn't too far away with a cross-cum-shot which whistled just past the far post.
The Baggies were frustrated in the 76th minute when Bednar raced onto Brunt's sublime throughball and fired past Lee.
The 'goal' was ruled out for offside - but TV replays showed both he and Phillips were onside.
Phillips had the next chance when he raced clear of the Watford defence to reach Gera's ball over the top, only to head weakly at Lee from just outside the box.
Albion went close again when Bednar flicked Brunt's centre across the face of goal.
And Gera went even closer in the 85th minute when he shaved the far post with a first-time 20-yard strike.
Another great chance went begging when Bednar sliced Brunt's neat ball into the box high over the bar with just Lee to beat.
But, try as they might, Albion could not muster another telling blow as the game petered out into a stalemate.
ALBION (4-4-2): Kiely; Hoefkens, Barnett, Clement, Robinson; Gera, Koren, Greening, Morrison (Brunt 67); Phillips, Miller (Bednar 73). Subs not used: Kim, Pele, Moore.
WATFORD (4-4-2): Lee; Doyley, Shittu, Bromby, Stewart; Smith, Eustace, O'Toole (Ellington 86), McAnuff (Kabba 86); Henderson, Priskin (Mariappa 66). Subs not used: Poom (gk), Sadler.
GOALS: ALBION - Barnett (49). WATFORD - Bromby (6).
BOOKINGS: ALBION - Koren (foul 25), Miller (foul 30), Hoefkens (foul 37), Barnett (dissent 85). WATFORD - Eustace (foul 44).
REFEREE: M Dean (Wirral).
ATTENDANCE: 26,508.
ALBION STARMAN: Paul Robinson.
PIC: KING LEON...Barnett celebrates his leveller
