The blazon of the municipal coat of arms is "Gules two Lions passant Argent." Zuzwil has a population (as of ) of . , about 10.3% of the population was made up of foreign nationals. Of the foreign population, (), 50 are from Germany, 73 are from Italy, 138 are from ex-Yugoslavia, 24 are from Austria, 20 are from Turkey, and 100 are from another country. Over the last 10 years the population has grown at a rate of 27.2%. Most of the population () speaks German (93.6%), with Albanian being second most common ( 1.3%) and Serbo-Croatian being third ( 1.0%). Of the Swiss national languages (), 3,556 speak German, 4 people speak French, 33 people speak Italian,  The age distribution, , in Zuzwil is; 592 children or 15.6% of the population are between 0 and 9 years old and 574 teenagers or 15.1% are between 10 and 19. Of the adult population, 397 people or 10.5% of the population are between 20 and 29 years old. 684 people or 18.0% are between 30 and 39, 623 people or 16.4% are between 40 and 49, and 487 people or 12.8% are between 50 and 59. The senior population distribution is 216 people or 5.7% of the population are between 60 and 69 years old, 133 people or 3.5% are between 70 and 79, there are 78 people or 2.1% who are between 80 and 89, and there are 14 people or 0.4% who are between 90 and 99. In the 2007 federal election the most popular party was the SVP which received 38.9% of the vote. The next three most popular parties were the CVP (20.4%), the FDP (18%) and the SP (10.4%). In Zuzwil about 80.4% of the population (between age 25-64) have completed either non-mandatory upper secondary education or additional higher education (either university or a "Fachhochschule"). Out of the total population in Zuzwil, , the highest education level completed by 665 people (17.5% of the population) was Primary, while 1,507 (39.7%) have completed their secondary education, 478 (12.6%) have attended a Tertiary school, and 113 (3.0%) are not in school.