Theoretical background: early verbal development is not yet fully understood, especially in its formative phase. Research question: can a reliable, easy-to-use coding scheme for the classification of early infant vocalizations be defined that is applicable as a basis for further analysis of language development? Methods: in a longitudinal study of 45 neurotypical infants, we analyzed vocalizations of the first 4 months of life. Audio segments were assigned to 5 classes: (1) Voiced and (2) Voiceless vocalizations; (3) Defined signal; (4) Non-target; (5) Nonassignable. Results: Two female coders with different experience achieved high agreement without intensive training. Discussion and Conclusion: The reliable scheme can be used in research and clinical settings for efficient coding of infant vocalizations, as a basis for detailed manual and machine analyses.