Although studies on English sound learning by L2 Thai learners have been widely examined, there have been no studies on the production of the English [ch] and [sh] sounds in the initial position by L2 Thai learners with consideration of vowel contexts, the experience of L2 learners and target sounds. The aim of this study is to examine the production of the English [ch] and [sh] sounds in the initial position while taking the aforementioned factors into account. The data was from 48 L2 Thai learners, and the subjects were divided into two groups of university students: English-majors and non-English-majors. The two target sounds: English [ch] and [sh] together with the Thai [characters omitted] sound were tested in 27 words (9 words for each target sound). The subjects produced the target sounds five times, and their production was transcribed by two British transcribers. The results showed that the subjects had high target-like production when producing [sh] but low target-like production when producing [ch]. In finding the correlation between the factors and the target-like production, neither the vowel contexts nor the experience could account for the production. The only factor that relates to the production of English [ch] and [sh] was the target sounds, i.e. the number of the productions that was deemed non-target-like was significantly higher when the target sound was [ch] than when it was [sh]. This suggests that the target sounds, rather than the L2 experience and the vowel contexts, play a significant role in L2 speech production.