If you go away and everyone in your environment only speaks one of your languages you will get better at all of your languages.<p>Languages are ways of communicating, if you can use more than one then your mind will start creating connections where they &quot;shouldn&#x27;t&quot; exist, i.e. &quot;everyone speaks english and spanish so I can use them interchangeably so it must be one language&quot; and you&#x27;ll start talking a hybrid language.<p>Regarding cognitive advantages of being multi lingual I&#x27;d say they are mostly related to abstractions and thinking patterns. You learn how to express yourself through different patterns and have new abstraction to understand the world around you. The same is true for learning any way of expressing yourself (not just languages but also math, programming, dancing, music, whatever...)<p>For example: Some people speak math+english as one language but most people don&#x27;t know the abstractions that they use even if they know &#x27;the language&#x27; (english) and therefore sometimes have a hard time understanding their way of thinking.<p>Sry english third language not prefect