Monthey has a population () of . , 29.0% of the population are resident foreign nationals. Over the last 10 years (2000–2010 ) the population has changed at a rate of 17.5%. It has changed at a rate of 16.2% due to migration and at a rate of 3.4% due to births and deaths. Most of the population () speaks
French (11,856 or 85.1%) as their first language,
Italian is the second most common (520 or 3.7%) and
Portuguese is the third (430 or 3.1%). There are 295 people who speak
German and 7 people who speak
Romansh. Of the population in the municipality, 4,611 or about 33.1% were born in Monthey and lived there in 2000. There were 2,769 or 19.9% who were born in the same canton, while 2,508 or 18.0% were born somewhere else in Switzerland, and 3,586 or 25.7% were born outside of Switzerland. , there were 5,949 private households in the municipality, and an average of 2.3 persons per household. , the construction rate of new housing units was 3.6 new units per 1000 residents. The vacancy rate for the municipality, , was 0.24%. == Sport and culture ==