Evidence-based answer · Last updated · How it’s made
Most of the sources here study Persian-speakers learning English rather than English-speakers learning Persian, but by looking at where the two languages' grammars, sounds, and writing systems clash, they still point to specific trouble spots an English speaker learning Persian is likely to hit: consonant clusters and syllable shape, articles/definiteness marking, relative clauses and word order, prepositions, and the Persian-Arabic script. There isn't a source that directly tests English speakers learning Persian, so this answer works by inference from contrastive-analysis studies — real but indirect evidence.
Asked as someone learning Persian (beta). Findings drawn from Persian-specific research are framed for Persian learners and may not hold for other languages; where the evidence is general second-language research, the report says so.
Persian syllables only allow one consonant at the start and at most two at the end, while English allows much bigger consonant clusters at both the start and end of syllables (like the 'str' in 'strengths'). This mismatch is documented as a major source of difficulty for Persian speakers learning English, and because the mismatch is symmetrical, it implies English speakers learning Persian would need to get used to a syllable system that is simpler in some ways but has different rules for where consonants can and can't cluster.6,10
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English marks 'the' vs 'a' mainly through grammar (syntax), while Persian expresses similar distinctions mostly through meaning and context (semantics) and different marking strategies, such as suffixes for specificity rather than a direct equivalent of 'the'. This deep structural difference is repeatedly shown to be one of the hardest things for Persian speakers to master in English, and it cuts both ways: an English speaker learning Persian cannot simply map 'the' and 'a' onto Persian equivalents one-to-one.1,3
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Persian allows a 'resumptive pronoun' strategy in relative clauses (roughly, restating the noun with a pronoun inside the clause) in places where English requires leaving a silent gap instead, and Persian question-like structures stay in place ('wh-in-situ') rather than moving to the front the way English does. Studies of Persian speakers learning English show this leads to a lasting preference for resumptive-style patterns even at advanced levels, driven more by real-time processing difficulty than by not knowing the rule.9,12
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Persian and English prepositions frequently diverge in ways that cause errors when moving between the languages — some Persian prepositions correspond to more than one English preposition and vice versa, some English prepositions attach to specific verbs with no predictable Persian counterpart, and there are also word-order differences (Persian has some postpositions and object markers that come after the noun, unlike English).4,8
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Persian is written in a modified Arabic script, read right-to-left, and research on Persian orthography argues its script has distinctive properties that shape how quickly reading skills develop, comparing it to how English's own famously irregular spelling affects reading development. Persian's letter-to-sound correspondence for basic reading is described as more regular than English's, though vowel marks are often left out of standard adult text, which is its own separate hurdle for a new reader.2,5
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Persian noun-noun compound words can be built with the 'head' (the main word that carries the core meaning) either first or last, and research shows the more common, easier-to-process pattern for Persian speakers is when the head comes last (head-final), with head-first compounds being processed more slowly and linked to a special connective element ('ezafe') in Persian compounding.7
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Research comparing how Persian-speaking English learners best acquire different grammar features found that exposure-based learning (seeing lots of correct examples) works better for smaller, word-level grammar features (like verb tense endings), while practice-based learning (actively producing sentences) works better for complex sentence-level structures (like relative clauses). One related study also suggested that grammar points where Persian and English are structurally more similar may respond especially well to active-practice methods.11,13
Example
Because most of the direct evidence here comes from Persian speakers learning English rather than the reverse, treat these as informed predictions about likely trouble spots rather than proven Persian-learning findings. Given the contrastive patterns found: (1) pay deliberate attention to Persian's syllable and consonant-cluster rules early on, since English speakers are used to different cluster patterns and may need focused listening and pronunciation practice rather than assuming clusters will transfer intuitively; (2) don't expect a direct one-to-one mapping between English 'a/the' and any single Persian marker — build a feel for definiteness and specificity through lots of reading and listening rather than trying to translate the rule; (3) treat relative clauses and question structures as a distinct grammar topic worth explicit study, since Persian's structure (resumptive pronouns, in-place question words) differs from English at a deep level and may take deliberate, repeated exposure and production practice to become natural; (4) study prepositions as their own vocabulary-like category with example sentences rather than relying on direct translation from English; (5) budget real time for learning the script itself, including practicing reading text with vowel marks omitted, since that is a separate skill from learning to speak; (6) when tackling any specific grammar point, match your study method to its complexity — lean on input (reading/listening to correct examples) for small word-level features and lean on active production (speaking/writing practice) for complex sentence-level structures.
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