title_body: Will I be able to read texts written in all Romance languages simply by learning Interlingua? Interlingua's official site claims that speakers of all Romance languages will immediately understand the language on paper when first exposed to it. Is this true? Can I really understand Spanish, Portuguese, Italian, Romanian, and French simply by learning a conlang?
  If it is true, then why isn't it more popular?
upvoted_answer: On their site it says:
  
  Millions understand Interlingua &quot;at first sight&quot;. Speakers of Romance languages especially understand Interlingua immediately and almost effortlessly. Ideal for traveling!
  
  So it's the other way round: if you speak a Romance language, Interlingua will make sense to you because it contains many elements (eg vocabulary) from these languages. This does not, however, mean that you can necessarily understand any Romance language after learning Interlingua, though I assume there will be some benefit going both ways.