Code-switching, switching between different languages within the same conversation, is a prominent feature in bilingual communication. This study aimed to elucidate to what extent the linguistic abilities and age of dual-language-learning preschoolers influence the frequency and purposes of code-switching (compensatory, to bridge linguistic gaps; preferential, to express content as fluently as possible; pragmatic, to phrase something appropriately for the situation). Parental code-switching ratings of 101 German/French–Turkish/Italian dual-language learners aged 32–78 months were analyzed. Generalized linear mixed models revealed positive but no negative effects of societal- and heritage-language skills on children's code-switching frequencies independent of switching purposes and with no evidence of age effects. Hence, code-switching across the preschool age mainly reflects high linguistic competences. Models with linguistically and psychometrically parallelized language scores indicated a strong switching tendency toward the societal language when proficiency in both languages is high, and away from the societal language when language proficiencies are low.

语码转换，即在同一对话中在不同语言之间进行切换，是双语交流的一个显着特征。本研究旨在阐明双语学习学龄前儿童的语言能力和年龄在多大程度上影响语码转换的频率和目的（补偿性，以弥合语言差距；优先性，尽可能流利地表达内容；务实性，以适合情况的措辞）。对 101 名 32-78 个月大的德语/法语-土耳其语/意大利语双语学习者的家长语码转换评分进行了分析。广义线性混合模型揭示了社会和传统语言技能对儿童语码转换频率的积极影响，但没有消极影响，与转换目的无关，并且没有年龄影响的证据。因此，学龄前阶段的语码转换主要反映了较高的语言能力。具有语言学和心理测量学并行语言分数的模型表明，当两种语言的熟练程度较高时，有强烈的转向社会语言的倾向，而当语言熟练程度较低时，则有远离社会语言的强烈转变倾向。