 Most of the population () speaks German (84.5%), with Italian being second most common ( 3.4%) and Serbo-Croatian being third ( 3.4%).Of the Swiss national languages (), 7,872 speak German, 27 people speak French, 313 people speak Italian, and 10 people speak Romansh.The age distribution, , in Flawil is; 1,216 children or 13.0% of the population are between 0 and 9 years old and 1,248 teenagers or 13.4% are between 10 and 19.