This document discusses the imperfect progressive tense in Spanish. The imperfect progressive, formed with the imperfect tense of estar plus a present participle, is used to describe an action that was ongoing or taking place over a period of time in the past. Some examples of using the imperfect progressive are provided, such as "Estaba esquiando cuando me caí" (I was skiing when I fell). The formation of present participles from stem-changing and spelling-changing verbs in -er and -ir is also reviewed.