Thailand fell to 62nd out of 70 nations in English proficiency and is now the third-worst country in Asia on Education First’s annual English Proficiency Index.
Even as countries such as Vietnam and India posted marked gains in English skills, Thailand's ranking fell the most in the Asian region, with the country now boasting better skills than only Cambodia and Mongolia on the list.
Worldwide, Thailand beat out only those countries, plus Qatar, Kuwait, Iraq, Algeria, Saudia Arabia and Libya.
"Thailand's English proficiency remains low despite the country's large tourism industry," stated the report from EF, an international education company specialising in language training, educational travel, academic-degree programmes and cultural exchanges.
"Thailand's school system performs poorly on international assessments across all subject areas. The average years of schooling there are also lower than the regional average, meaning that Thai adults are less educated than many other Asians."
Education First noted that Thais still exhibit poor English skills even though the country spends a greater percentage of its budget -- 31.3% -- on education than any of the 70 countries it surveyed.
"A low (gross national income) per capita means that although the elite can invest in private schools and English tutoring, those options are not available to everyone," EF said.
The company noted the current government now has mandated that schools align their English teaching to the Common European Framework of Reference for Languages in order to standardise teaching nationally.
The government also has set a "modest" goal of a B1 level in English for all high school graduates, EF said.
Source: Education First English Proficiency Index
The English rankings, released for the fifth consecutive year, were derived from test data collected from more than 910,000 adults who took the company's online English tests in 2014.
"Few countries continue to debate whether or not English should be taught. Instead, discussions of English instruction in public schools focus on which dialect of English is taught, how it is assessed, and how much English education is necessary," the report said. "In developing countries, English is often tied to development goals, expansion of the service sector, and increased connectivity to the rest of the world."
As is the case globally, women in Thailand speak better English than men, 46.3% to 44.3%. Global proficiency averages for women and men, respectively, however, are 53.4% and 52.1%.
The country's decline in English proficiency can be seen in age breakdowns. Youths 18-20 years old and adults 21-25 exhibit poorer English skills than those in the 26-30 age bracket.
Globally both those age groups do better with English, EF found.
Average scores on the international TOEFL and IELTS scores in Thailand came in at 76 and 5.3, respectively. TOEFL scores among the surveyed countries ranged from a low of 61 to a high of 100.