This chapter discusses number in pidgins, pidgincreoles, creoles and mixed languages. It will show that it is more common for most of these languages to mark number in pronouns than in nouns. Clusivity, however, is not commonly marked for any of these languages. Pidgin languages tend to not have nominal plural marking, nor agreement marking in verbs or modifiers. The associative plural is not common for pidgins. Nominal number tends to be optional for pidgincreole and creole languages, typically marked with a plural word. The associative plural is common for both pidgincreoles and creoles. As for number agreement and syntax, adjectives tend to remain in their base form for both creoles and pidgincreoles, and verbs are typically not marked for number agreement. Determiners, however, do tend to show number agreement with their head. Coordinating constructions are not redundantly marked for number. Mixed languages tend to reflect the system of one of the input languages. Generic expressions tend to remain in the base form in all these languages. Pidgins and pidgincreoles do not tend to mark politeness distinctions. Creoles, however, may optionally express politeness through the plural form. Politeness distinctions do not seem common in mixed languages.