A Linguist Explains: Are Some Languages More Difficult Than Others?

Before comparing languages, linguists distinguish between complexity and difficulty. Complexity refers to characteristics of the language itself. A grammatical system might contain many verb forms, noun classes, tones, or rules for word order. Difficulty, by contrast, refers to the cognitive effort required for a person to learn or use those features. As Bulté et al. (2025)↗ explain, a structure can be formally complex without being equally difficult for every learner. The two concepts are related, but they are not interchangeable.

Italian verbs, for example, have more distinct endings than English verbs:

Io parlo — I speak Tu parli — you speak Lui/Lei/L* parla — he or she speaks Noi parliamo — we speak Voi parlate - you all speak Loro parlano - they speak

English usually expresses the same information with separate pronouns and comparatively little change to the verb. An English-speaking learner may initially find Italian conjugations complicated. A Spanish speaker, however, is already familiar with a similar system and may find them much more predictable. A feature that feels difficult may therefore be difficult not because it is objectively exotic, but because it is unfamiliar.

One of the strongest influences on second-language learning is the relationship between the language you already know and the language you are learning. Italian and Spanish share vocabulary, grammatical patterns, and many sounds because both developed from Latin. An Italian speaker may quickly recognize Spanish words. English and Dutch also share significant vocabulary and structural features because both belong to the Germanic language family. When two languages are closely related, learners can transfer some of their existing knowledge. They do not have to build every pattern from the beginning. (More on Intercomprehension soon!!) By contrast, a learner may need more time when the new language uses unfamiliar sounds, grammatical categories, or word-order patterns.

Schepens et al. (2023)↗, examining Dutch learners from 50 first-language backgrounds, found that linguistic dissimilarity influenced adult language-learning outcomes. Differences in vocabulary, morphology, and phonology all contributed to the learning challenge. This helps explain why Japanese may take longer for an English speaker to learn than Dutch. The issue is not that Japanese is inferior, illogical, or impossibly complicated. It is simply more distant from English in several important respects. For a Korean speaker, the comparison could look different. Japanese shares some word-order patterns and grammatical features with Korean, which may make parts of the language more familiar.

Every “hardest language” list silently assumes a particular kind of learner. Every language distributes complexity differently. Languages do not all place complexity in the same areas. A language with relatively simple verb conjugations might have unpredictable spelling. Another might have highly regular spelling but an extensive system of noun endings. A language with flexible word order may use grammatical markers to show who is doing what to whom. A language with fewer word endings may depend more heavily on a fixed word order.

English nouns have relatively little grammatical gender and case marking, but English spelling presents learners with words such as though, through, thought, and tough. Mandarin verbs do not conjugate for person in the way Italian verbs do, but changes in pitch can distinguish word meanings. Japanese pronunciation is often considered relatively accessible, while its writing system requires knowledge of multiple scripts. These differences make it difficult to calculate the total complexity of an entire language. A language may appear simple when researchers examine one feature and complicated when they examine another.

Speaking, reading, and writing may have different levels of difficulty. When someone says a language is difficult, it is important to ask which skill they mean. Learning to pronounce a language is not the same as learning to read it. Holding an everyday conversation is not the same as writing an academic essay. A learner may become comfortable speaking while still struggling with spelling, or may read complex texts without understanding rapid informal conversation. Writing systems create particularly visible differences.

Spanish and Italian have relatively transparent spelling systems: once learners know the major sound-letter correspondences, they can often pronounce an unfamiliar written word reasonably accurately.

English has a deeper, less predictable orthography. The same letters can represent different sounds, and the same sound can be spelled in multiple ways. Seymour et al. (2003)↗ compared children learning to read in several European languages and found that foundational reading developed more slowly in languages with deeper orthographies, especially English, than in languages with more consistent sound-spelling relationships. This does not make English as a whole more difficult than every other language. It means that one particular part of English—learning to decode its writing system—creates a substantial challenge. Conversely, a learner of Mandarin may find some aspects of spoken grammar accessible while needing considerable time to become literate in Chinese characters. The difficulty also depends partly on the learner’s goal. Someone preparing for a vacation, an interpreter, and a student of classical literature are not trying to master the same skills.

Children and adults learn languages under very different conditions. Young children receive thousands of hours of interaction, usually without being expected to memorize grammar tables or perform on a test. Adults often have less time, more self-consciousness, and fewer opportunities to use the language. At the same time, adults possess literacy, study strategies, and explicit grammatical knowledge that can help them make rapid initial progress.

Research suggests that the capacity to acquire a language remains strong longer than popular accounts sometimes imply. In a large-scale study involving approximately two-thirds of a million participants, Hartshorne et al. (2018)↗ found that the ability to learn English grammar remained relatively robust through childhood and adolescence before declining in late adolescence. Starting young increases the likelihood of achieving completely native-like proficiency, partly because young learners have more years of exposure before adulthood. But this does not mean that adults cannot become highly proficient.

Motivation, quality of instruction, meaningful interaction, time, identity, and access to a linguistic community can all affect progress.

The difficulty of a language is therefore not located entirely inside the language. It emerges from the relationship among the language, the learner, the learner’s goals, and the environment in which learning occurs. Perhaps the best answer is this: the most difficult language is often the one you have the fewest opportunities to use. And the easiest? Probably the one that becomes part of your life.

References:

• Bulté, B., Housen, A., & Pallotti, G. (2025). Complexity and difficulty in second language acquisition: A theoretical and methodological overview. Language Learning, 75(2), 533–574. ↗
• Hartshorne, J. K., Tenenbaum, J. B., & Pinker, S. (2018). A critical period for second language acquisition: Evidence from 2/3 million English speakers. Cognition, 177, 263–277. ↗
• Schepens, J. J., van Hout, R. W. N. M., & van der Slik, F. W. P. (2023). Linguistic dissimilarity increases age-related decline in adult language learning. Studies in Second Language Acquisition, 45(1), 167–188. ↗
• Seymour, P. H. K., Aro, M., & Erskine, J. M. (2003). Foundation literacy acquisition in European orthographies. British Journal of Psychology, 94(2), 143–174. ↗