The Frisian languages family consists of North Frisian, Saterland Frisian and West Frisian. All three languages display a morphological and syntactic distinction between two types of infinitives:

• Ordinary infinitives
• Gerundial infinitives

Here Frisian contrasts with German and Dutch. In the latter two languages, all infinitives have the same ending, spelled (e)n. Saterland Frisian, like West Frisian, makes a morphological distinction between ordinary infinitives, which end in -e, and gerundial infinitives, which end in -n. The type of ending has consequences for the syntactic distribution of infinitives and for its complementation in Saterland Frisian.

The ordinary infinitive in Saterland Frisian ends in schwa, spelled -e, or in a handful of monosyllabic cases, in -o. The verbs in -o are: dwo ‘do’, geskjo ‘happen’, krjo ‘crow’, mjo ‘mow’, sjo ‘see’, slo ‘hit’, and verbs derived from them. The gerundial infinitive always ends in -n. In West Frisian there are seven verbs for which the distinction is neutralised, but for Saterland Frisian the distinction is made without exception. The choice of infinitive is a matter of syntactic selection. Modal verbs and the causative verb läite ‘let’ select the ordinary infinitive, which is glossed as OI. Two examples are given below:

In addition, the citation infinitive is in schwa as well, which is also used as a fragment answer to a question like: what are you doing:

Verbs of perception and the infinitival marker tou ‘to’ (among others) select the gerundial infinitive, which may be shorted to 'the gerund', glossed as GI:

The definite article and the demonstrative article select the gerund, which is illustrated below for the definite article:

This is an outline of the distribution of the two infinitives, but the actual distribution is more complex: for this, see The VP in Saterland Frisian. The selecting head (modal verb, verb of perception, and so on) plays a key part in determining the distribution of the two types of infinitives. It is hard to acquire this distribution as a second language speaker.

Ordinary infinitives may not be nominalised. As a result, complements of ordinary infinitives are licensed like complements to verbs. In contrast, complements of gerundial infinitives can be licensed like complements to nouns.

Gerundial infinitives may be nominalised. As a result, complements of gerundial infinitives may be licensed as complements to nouns are. So, the subject can be realised as a possessor in case it is a person:

Both the subject and the object can be realised in a PP headed by fon ‘of’:

The first example above features a PP that bears the thematic role of the subject, whereas the second example features a PP that bears the thematic role of the direct object. A gerundial infinitive may show up in all argument positions. The following examples respectively involve a gerundial infinitive in subject position, object position and as a prepositional complement.