Apenheul Primate Park in the Netherlands is well known for its 40 year-old tradition of keeping various primate species in semi-natural conditions and free ranging among visitors. Most of the free-ranging primates at Apenheul are cebids and they are the focus of this article. Factors to consider when mixing primate species in a free-ranging exhibit, such as enclosure design, husbandry and management measures related to visitors, are presented. Those details are thought to be crucial for this form of keeping primates to succeed. The possibilities and challenges of keeping primates free ranging in the natural social setting are discussed. Mixing different animal species in one area can improve the visitor experience and can also be valuable enrichment for the animals themselves. The species combinations (primates mixed with other primate species as well as with non-primate species) that Apenheul has had experience with since the opening in 1971 are listed in two tables. Advice is given on issues to consider if institutions want to mix primate species in a semi-free-ranging exhibit.