When learning English as a foreign language, the ability to accurately produce lexical stress is crucial for achieving speech rhythm and ensuring clear communication. This skill presents a distinct challenge for learners whose native languages lack lexical stress, such as French and Japanese. Regrettably, due to time constraints and limited teacher training, stress often receives less attention than grammar and vocabulary in language instruction. In this study, we introduce a processing pipeline designed to automatically assess the position and quality of lexical stress in spontaneous L2 English speech. Following an automatic speech recognition and syllable alignment phase, fundamental frequency (F0), intensity and duration of each syllable are extracted to derive the word’s prosodic shape. This shape is then compared with the expected canonical shape(s) of the word within its syntactic context, using a reference dictionary. Furthermore, the degree of contrast between each syllable in the word is measured across the three prosodic features, providing insights into the quality of stress and reduction patterns. The pipeline was implemented on a sample of 176 French learners of English at the B1 and B2 CEFR proficiency levels, engaging them in spontaneous discussion scenarios. The results uncovered that only 35.4% of polysyllabic lexical words (out of 6,424 target words) carried stress on the appropriate syllable. Speaker displayed considerable diversity, with overall stress placement accuracy ranging from 0% to 68.4%. A significant improvement was observed from B1 to B2, as the median of speaker stress placement accuracy is 29.6% at the B1 level and 36% at the B2 level (non-parametric rank test, p<.001). Most students tended to lengthen the final syllable of words, disregarding the expected stress pattern. Only speakers demonstrating proficient stress placement utilized F0 and intensity parameters to stress syllables. This pipeline constitutes the initial stride towards an improved system, which will subsequently be integrated into a pronunciation training system for enhancing L2 English instruction, fostering the development of more fluent speech rhythm and enhanced intelligibility for learners.