The present paper reports on a case study investigating the acquisition of form and function of the English progressive by a seven-year-old Hebrew speaker, learning English as a second language. The paper describes the different elicitation techniques used, and discusses the suitability of such techniques for the investigation of form and function. As a result of the study, a developmental sequence in the subject's acquisition of the progressive is established. The sequence exhibits clear stages in the acquisition of form but less distinct ones in the acquisition of function. The paper calls, therefore, for further study of the developmental sequence in the acquisition of the English progressive, with the overall goal of arriving at a valid index of development for the beginning ESL learner. (Author)