Students from as far afield as Poland, Hungary, Holland and Spain celebrated their achievements at an awards ceremony.
The students are taking 10-week qualifications in academic English at Uxbridge College, and come to classes two nights a week.
The students picked up certificates for their achievements in studies following the University of Cambridge First Certificate syllabus.
Marek Drozd (23), from Poland is studying English while making a living as a builder and decorator, and has been in the UK for eight months.
Marek, who lives in Hayes, said: "In England you get a better salary, and it is easier finding a job.
"I wanted to improve my English and my friend encouraged me to go to college. I have learned a lot and I feel that my English has improved.
"I have been living and working with Polish people so I had no opportunity to speak English, so it is good to take the course."
Izabela Szydelko (19), who lives in Greenford, came to England in July intending to leave after the summer and take up a university place in Poland, but decided she would stay to improve her language skills.
She works on a travelling market stall selling fruit and nuts, and in shops selling the same produce in and around London, called Golden Raisins.
She said: "The first reason I came to England was to improve my English in a practical way. I learn through my work as well as at college."
Izabela hopes to take a more advanced qualification, the Cambridge Advanced Examination, at the College next year.
Giles Strachan, ESOL (English for Speakers of Other Languages), Section Manager for Outreach, said: "These students are people who are determined to speak excellent English that they can use in employment or further study. Nearly everyone has a job as well as studying and they have really shown their commitment to improving their language skills. Congratulations to everyone on the course."