This is one of the most persistent myths in the Spanish-speaking world. And from a linguistic perspective, it’s completely false.

While Castilian Spanish has a unique and important place in the language’s history, it is not linguistically superior. To understand why, we need to unravel the difference between a language standard born of political power and the natural, beautiful chaos of linguistic evolution.

Where Did This Idea Come From? The Power of Castile

The myth of Castilian purity isn’t born from nothing. It has deep roots in the history of Spain itself. During the Middle Ages, the Iberian Peninsula was a mosaic of different kingdoms and languages. As the Christian kingdoms of the north began the centuries-long process of pushing south to retake territory from the Moorish rulers—a process known as the Reconquista—one kingdom emerged as dominant: Castile.

As the Kingdom of Castile expanded, its dialect of Ibero-Romance (the precursor to modern Spanish) naturally spread with it. The turning point came in the 13th century with King Alfonso X, known as “El Sabio” (The Wise). He established a royal scriptorium in Toledo and decreed that the Castilian dialect be used for all administrative, legal, and scholarly works. This was a crucial first step in standardization. He wasn’t choosing the “best” dialect; he was choosing the dialect of the most powerful court.

Two centuries later, in 1492—a year famous for other reasons—the first grammar of a modern European language was published: Antonio de Nebrija’s Gramática de la lengua castellana. In his introduction to Queen Isabella I of Castile, Nebrija famously wrote that “language is always the companion of empire.”

This history gave the Castilian dialect immense prestige. It became the language of power, literature, and empire. But prestige is a social and political construct, not a linguistic one.

What Exactly *Is* Castilian Spanish?

When people refer to “Castilian Spanish”, they are generally talking about the variety spoken in north-central Spain. It has a few distinctive features that set it apart from most other dialects, especially those in Latin America:

• The Distinción: This is the most famous feature. The letter ‘z’ and ‘c’ (before ‘e’ or ‘i’) are pronounced as a voiceless ‘th’ sound, like in the English word “think.” The letter ‘s’ retains its ‘s’ sound. So, cinco (five) and zapato (shoe) have a different sound from siento (I feel). In most of Latin America and southern Spain, this distinction doesn’t exist; all three letters are pronounced with an ‘s’ sound (a phenomenon called seseo).
• The Pronunciation of ‘ll’: In more traditional Castilian, the ‘ll’ is pronounced as a distinct sound, different from ‘y’ (though this is fading among younger generations, who often merge them in a process called yeísmo).
• The Use of Vosotros: For the informal second-person plural (“you all”), Castilian Spanish uses vosotros (e.g., ¿Qué hacéis? – What are you all doing?). In almost all of Latin America, ustedes is used for both formal and informal situations.

These features are simply regional variations—no different from a person from London saying “tomahto” and a person from Chicago saying “tomayto.”

The Journey Across the Atlantic: A Different Evolution

When Spanish crossed the ocean in the 16th and 17th centuries, it wasn’t a single, monolithic “pure” language that was exported. The colonists, soldiers, and administrators who traveled to the Americas came from all over Spain. A huge number, however, came from the southern regions, particularly Andalusia and Extremadura.

This is key. The Spanish of Andalusia has always been a bit different from the Castilian of the north. For example, Andalusians don’t make the distinción—they have seseo, just like Latin Americans. The main port for voyages to the Americas was Seville, in the heart of Andalusia. It makes perfect sense that the speech patterns of southern Spain would have an outsized influence on the Spanish that took root in the New World.

Once in the Americas, Spanish didn’t just sit still. It evolved for 500 years in parallel with the Spanish in Spain. It was shaped by new environments and new contacts:

• Indigenous Languages: Spanish adopted thousands of words from languages like Nahuatl (chocolate, aguacate, tomate), Quechua (cancha, papa, cóndor), and Taíno (canoa, huracán, maíz).
• African Languages: The transatlantic slave trade brought African linguistic influences, particularly in the Caribbean, affecting rhythm, intonation, and vocabulary (e.g., chévere, bachata).
• Isolation and Innovation: Different regions developed their own unique slang, grammar, and pronunciation. Argentinian and Uruguayan Spanish developed voseo (the use of vos instead of tú) with its own unique verb conjugations.

The Spanish of Bogotá, Lima, and Mexico City are not corrupted versions of Madrid’s Spanish. They are all sibling dialects that share a common ancestor: Old Spanish.

So, What Is “Correct” Spanish?

Linguists make a crucial distinction between a standard language and linguistic correctness. A standard is a variety of a language that is promoted in formal contexts like government, media, and education for the sake of mutual intelligibility across a wide area. The standard for Spanish, historically centered on the Castilian norm, is now governed more collaboratively by the Real Academia Española (RAE) and its 22 associated academies across Latin America and the Philippines.

Importantly, the RAE’s role today is more descriptive than prescriptive. It documents how the language is actually used by its 500 million speakers, acknowledging and accepting vast regional variation. The official dictionary includes thousands of americanismos.

“Correctness”, then, is about context. Using vosotros in Mexico is not “more correct”; it’s just out of place. Similarly, asking for a popote (straw) in Spain will get you a blank stare, where you should ask for a pajita. Neither term is intrinsically better—they are just part of different, equally valid regional dialects.

Think of it like English. Is the Queen’s English more “original” than Australian, Canadian, or American English? Of course not. They all evolved from a common source and went their separate ways. The same is true for Spanish.

A Family of Languages, Not a Monarchy

The idea of a “pure” Castilian Spanish is a relic of an imperial mindset that conflates political power with linguistic worth. The Spanish language is not a monarchy with Castile as its king. It’s a vast, vibrant, and diverse family of dialects, each with its own history, flavor, and logic.

For learners, this is great news. It means you are free to learn the dialect that is most useful or interesting to you. Whether you learn to speak like someone from Spain, Colombia, or Argentina, you are learning real, authentic, and complete Spanish. So embrace the diversity, celebrate the differences, and enjoy the rich tapestry that is the Spanish language.