ABSTRACT Purpose: this study used the ultrasonography of the tongue movements and the dynamic models of speech production to characterize the articulatory gestures of in the production of /l/ at the Brazilian Portuguese in different age groups, comparing them between typical and atypical children. Methods: the sample consisted of 30 typical and 30 atypical children between ages of four and eight-years-old, who underwent speech-language and ultrasonographic evaluations. The evaluation was realized by recording words reproduction with the sound /l/ and the following vocalic contexts: /a/, /i/ and /u/, repeating six times for each word. The software for recording and analysis was Articulate Assistant Advanced (AAA). The quantitative analysis considered the 42 points that intercepted the tongue curves in each image to describe the articulatory gestures; the estimation of the mean lines of each curve and the confidence intervals between typical and atypical children groups; and the differences between the mean tongue contours curves according to age group. Results: the results presented a tongue tip elevation and dorsal and root retraction in /l/. Typical children, regardless of age, showed a greater refinement of articulatory tongue gestures than the atypical ones. In older children, there was more delimitation in the mean tongue contours from the tongue tip to the root. Conclusion: the ultrasonography of the tongue movements is a substantial implement to characterize the articulatory gestures of /l/, to the differentiation between typical and atypical productions in this sound, and observation of the development of the articulatory gestures.