Children are active learners: They selectively attend to important information. Rhythmic neural tracking of speech is central to active language learning. This chapter evaluates recent research showing that neural oscillations in the infant brain synchronize with the rhythm of speech, tracking it at different frequencies. This process predicts word segmentation and later language abilities. We argue that rhythmic neural speech tracking reflects infants’ attention to specific parts of the speech signal (e.g., stressed syllables), and simultaneously acts as a core mechanism for maximizing temporal attention onto those parts. Rhythmic neural tracking of speech puts a constraint on neural processing, which maximizes the uptake of relevant information from the noisy multimodal environment. We hypothesize this to be influenced by neural maturation. We end by evaluating the implications of this proposal for language acquisition research, and discuss how differences in neural maturation relate to variance in language development in autism.