The conference, at the Royal College of Physicians in Edinburgh, is expected to highlight the benefits to society of enabling offenders to repay their debts to local communities.
Professor Kathleen Marshall, commissioner for children and young people, will also lead a workshop this afternoon on the rights of prisoners' children.
MacAskill said the conference was coming at an important time when alternatives to sending people to prison needed to be sought.
"The theme of this conference is absolutely vital to the Scottish Government's agenda," he said.
"I recently visited Barlinnie and Cornton Vale and witnessed the impact that overcrowding is having on our hard working prison staff as they try to rehabilitate serious and dangerous offenders.
"This conference takes place against the backdrop of a prison population which is breaking records on a near daily basis. Although crime has fallen we are locking up more people than ever.