Later this month, members and supporters will be joined by current and former politicians who have represented the Goulburn Valley at the state and federal level.
Former state Member for Shepparton Don Kilgour has collated a history booklet and will emcee the lunch.
The Tallygaroopna branch is a tight group of people. Unlike surrounding Nationals branches that have folded, Tallygaroopna has held strong despite declining numbers.
One example is secretary Glenda Dempster and her family, which has held the secretary position since inception.
“I've been secretary for more than 25 years,” Mrs Dempster said.
“My father, Keith Crozier, was secretary for 25 years and his cousin George Billingham was secretary for about 50 years.
“It's just something I grew into. Dad wanted to get out was because he was getting older and I was one of the younger ones at the time.
“I wasn't even elected, I was at a tennis meeting at the time. I came late and as soon as I walked in Bruce Lloyd started clapping and said 'here's our new secretary'.
“I'd always been party of the branch because I would come along and help the older ladies with supper. My husband, Noel, was a member since before we were married.
“Noel has been vice-president for 47 years."
The Tallygaroopna branch was founded in 1919 but at the time as a branch of the Victorian Farmers Union.
From about 1927 it was known as the Country Party until 1975 when it became the Nationals.
The 100th celebration is being held at the Soldiers Memorial Hall on Sunday, October 27 from 11.30am.
RSVP by Friday, October 18. Tickets cost $30; phone Mrs Dempster on 03 5829 8330.