Boom, 30, previously raced with Rabobank, which morphed into Blanco and then Belkin, but left the team before it gained its current title sponsors in 2015.
"Lars Boom returns very motivated to his old nest," Technical Director Nico Verhoeven said. "He proved in the past that he's able to deliver strong performances in the spring Classics and together, we want to take the final step to win a big classic race.
"He's a multifunctional rider. He can play a role in the sprint train and in Grand Tours. Besides that, we want to bring his time trial back to a level that allows him to fight for victories again."
Boom began his career in cyclo-cross and was world champion in 2008 when he announced his intent to focus fully on the road with Rabobank. He won a stage in the Vuelta a España in 2009, and has won prologues in Paris-Nice, the Critérium du Dauphiné and Tour of Qatar, the overall Tour of Britain, Eneco Tour and Ster ZLM Toer, but the pinnacle of his success came in the 2014 Tour de France, when he won the rainy, cobbled stage to Arenberg.
The victory confirmed his promise in the Classics, and he was fourth last year in Paris-Roubaix, but a major one-day victory has so far eluded him.
"After two years with Astana, I expect to feel comfortable in the Classics," Boom said. "The support and confidence the team gives me plays a big role in that feeling. There's something missing on my palmarès, and that's a victory in the big Classics. Besides that, I want to get back to working on my time trial together with the team. It's great to see how much the team invests in the development of the time trial bikes and specific training."
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Boom said he feels good about returning to the Dutch squad. "The team took some big steps in its development over the last two years while I was away. Look at the sprint train with Dylan Groenewegen and the performances in the Grand Tours with Robert Gesink and Steven Kruijswijk."
