Abstract
<jats:title>Abstract</jats:title> <jats:p> It is a standard assumption of construction grammar that grammar constitutes a network, known as the constructicon. Thus far, research on the constructicon has been mainly concerned with the taxonomic organization of grammar. However, a number of recent studies have argued that the constructicon is not only a taxonomy of hierarchically related grammatical patterns but that it also includes horizontal relations between constructions at the same level of abstraction (e.g., <jats:xref>Cappelle, 2006</jats:xref> ; <jats:xref>Diessel, 2019a</jats:xref> ; <jats:xref>Sommerer & Smirnova, 2020</jats:xref> ; <jats:xref>Van de Velde, 2014</jats:xref> ). Building on this view, the current paper argues that horizontal relations are crucial to the analysis of two general phenomena of grammar: construction families and grammatical paradigms. Construction families are groups of similar constructions that share some of their semantic and formal properties, whereas grammatical paradigms are pairs, or sets, of alternating constructions that profile a particular contrast or set of oppositions. Psycholinguistic evidence for horizontal relations comes from research on syntactic priming, linguistic productivity, blocking (or preemption), and neighborhood effects in language use and acquisition. </jats:p>