Henry Marshall picked up three wickets but Worcestershire Under-17s were held up by the Somerset middle-lower order on the opening day of the Specsavers County Championship match at Stourport.
Somerset were 190-6 at one stage after opting to bat but recovered to declare at 341-9 and picked up an early wicket as Worcestershire closed on 9-1.
Mitchell Stanley made an early breakthrough with only eight runs on the board and wickets fell at steady intervals until Ned Leonard and Josh Thomas joined forces and put on 75 for the seventh wicket.
Leg spinner Josh Dickenson broke the partnership by bowling Thomas (51) at 265-7.
But Leonard was joined by Noah Davies (32 not out) and a further 61 runs were added for the eighth wicket.
Henry Marshall claimed his third scalp of the day when he trapped Leonard lbw for 71 off 113 balls with 12 fours shortly before the declaration.
Henry Marshall finished with excellent figures of 18-4-44-3, Stanley 14-2-56-2, George Marshall 14-3-56-1, Dickenson 25-3-78-1, Pete Clark 12-1-45-1 and Josh Baker 5-0-12-1.
Worcestershire were left with seven overs batting at the end of the day and lost Rehan Edavaleth for a duck.