Northamptonshire have been promoted to Division One of the LV= County Championship after Essex were bowled out for 207 against Hampshire.
Essex needed to get maximum batting points and win their clash at the Ageas Bowl, but fell well short of the 400 runs that were required in their first innings.
Loanee Matt Coles returned figures of 6-71 as the hosts took a first-innings lead of 249 before compounding Essex's woes by making them follow on.
Northamptonshire had secured a first-innings advantage of 39 against Worcestershire but no longer need to get a positive result to ensure their promotion.
The achievement caps a highly-successful year for the county, who also took the Friends Life t20 crown in August.
"We've been competitive in all three competitions (this season) so we've played pretty consistent cricket all year round," Northamptonshire head coach David Ripley told Sky Sports News.
"We stuttered a bit at the end. We wanted to get over the line in a bit of style and we've kind of stuttered over, but we're there. It's a great effort and a great feeling."
He added of Northants' improved fortunes this year: "It's a little bit of belief from the players. You win games, your confidence goes up and you win more games.
"We planned a little bit more thoroughly for one-day cricket - we took that view and we've probably practiced our skills more in that than four-day cricket.
"But we've had a pretty good four-day side. We've missed out by the odd point over the last four years or so.
"We felt the nucleus was there in four-day cricket and it's nice to put the icing on the cake."