This paper discusses the acquisition of Mandarin lexical tones by American second language(L2)learners.The analy sis of the tone errors in the reading p assa g e and the spontaneous speech showed that the surface Tone 4error is the most frequent at the prosodic word(P W)-initial position in both the intermediate and the advanced learner group s.Attempts were made to account for this tone error p attern within some second language acquisition(SLA)frameworks,but in vain.It was arg ued that this tone error pattern may be due to the high pitch tendency at the p hrase-or sentence-initial position in speech.Although this is more of ageneral pattern across languages,the production of such a tendency by L2 learners sup erseded the underly in g tones,hence the surface Tone 4errors.The sp ecial status of Tone 4in L2 sp eech corres ponds to the special status of the same tone in the first language(L1)speech(Wan,2007).However,it was cautioned that such similarity should not be taken as evidence for the similarity in L1 and L2acquisition in that different processes are involved in L1 and L2production. This paper discusses the acquisition of Mandarin lexical tones by American second language (L2) learners. The analy sis of the tone errors in the reading p assa ge and the spontaneous speech showed that the surface Tone 4 error is the most frequent at the prosodic word ( PW) -initial position in both the intermediate and the advanced learner group s. Attempts were made to account for this tone error p attern within some second language acquisition (SLA) frameworks, but in vain. It was arg ued that this tone error pattern may be due to the high pitch tendency at the p hrase-or sentence-initial position in speech .Although this is more of ageneral pattern across languages, the production of such a tendency by L2 learners suprserated the underly in g tones, therefore the surface Tone 4errors. the sp ecial status of Tone 4in L2 sp eech corres ponds to the special status of the same tone in the first language (L1) speech (Wan, 2007) .However, it was cautioned that such similarity should not be taken as evidence fo r the similarity in L1 and L2 acquisitions in that different processes are involved in L1 and L2 production.