This article discusses a phenomenon which has been referred to as ‘double determination’, ‘double definiteness’, or in the Scandinavian tradition ‘over-definiteness’. In this article, I define double determination and double definiteness, so that a distinction is made between the two terms. I use ‘double determination’ when both elements can function independently as semantic determiners. ‘Double definiteness’, on the other hand, is a form of agreement. A number of Swedish constructions are then examined which are plausible candidates for double determination. It is shown that only some of these are genuine cases of double determination, the others are more accurately described as double definiteness. In the cases of double determination, the determination is represented once as a syntactic element and once as a morphological element. The second part of this article focuses on this ‘morphological determiner’, referred to as def. The Swedish morphological determiner is compared with those of the other Scandinavian languages and the languages of the Balkans. It is shown that in languages which have an element like the Swedish def there is considerable variation in how this element functions within the language and in its status with respect to double determination and double definiteness.