For the current study, a multi-measure, micro-analytic approach was used to prospectively explore the role of preliminary symbolic play with single and multi-objects in language milestone development and vice versa. Fourteen infants followed up in monthly one hour sessions between the ages of 8 and 16 months. Their spontaneous play acts and vocal behaviors were recorded, enabling the coding of vocalization, babbling, and speech. A multivariate model was used to examine the mutual link between the play and language milestones. The results indicated a general reciprocal support tendency between the lingual and play behaviors; however, the simplest forms, vocalization and single-object play, were found to have key roles in cognitive development. Vocalization and babbling were found to correlate with both play forms, and play with a single object was related to the production of all vocal behaviors. The discussion explains the mechanisms of vocalization and single-toy play that enable cognitive growth.