The talks, at the Mount Kumgang resort in the North, will focus on plans to build a permanent meeting place for families that have been separated for more than 50 years.
Millions of people were separated from their families after the division of the Korean peninsula in 1945, and the Korean War in the early 1950s.
The talks come as South Korean President Kim Dae-jung said on Friday that he believes inter-Korean relations were now back on track and that he was optimistic about the future.
Reunion venue
The first reunions for relatives took place after a summit between the two Koreas in 2000, but so far only a few thousand people have been able to take part in them.
South Korea's Red Cross chief, Suh Young-hoon, said before leaving for the three-day meeting, that there was a "consensus" between the two sides that a permanent reunion venue needed to be established.
He added that this would "help end as early as possible this tragedy [of separated families] which is unprecedented in world history".
North Korea has proposed a reunion place at Mount Kumgang - the scenic resort on the country's east coast, to which South Korea already runs tours.
Mr Suh indicated that he would accept this proposal, but also hopes to build another meeting place on the South Korean side of the border, at Dorasan train station.
He also said that he would propose holding the reunions twice a month.
Letter exchange
Other issues on the agenda include the next reunions - for 100 separated family members - due to be held at Mount Kumgang before 21 September, and allowing a regular exchange of letters across the border.
The latest reunion was agreed at cabinet level inter-Korean talks in Seoul last month, which marked a new rapprochement between the two sides.
On Friday Mr Kim said that while North Korean behaviour remained unpredictable, he believed that the regime seriously intended to implement the agreements made at the two sides' historic summit in 2000.
He said he believed Pyongyang was genuinely trying to change its behaviour, seen by recent efforts to improve diplomatic ties with the US and Japan - Japanese Prime Minister Junichiro Koizumi will visit later this month - as well as its undertaking of various economic reforms.