Based on the Writer(s)-within-Community Model, this article focuses on the role of handwriting in writers' composing process. With the goal of highlighting the importance of researching and promoting handwriting, we provide an extensive summary of current evidence on the topic. It is well established that an important condition for skilled writing is handwriting automaticity. As here reviewed, there are at least four reasons why poor and slow handwriting can interfere with writing: it has a negative impact on the reader, creates a mismatch between ideas generation and recording, imposes heavy demands on working memory, and turns writing into a painful experience. Grounded on this, we make the case for providing child and adolescent writers with explicit and systematic practice in handwriting through evidence-based practices. The best practices at the letter (e.g., alphabet exercises), word/sentence (e.g., copying exercises), and text (e.g., authentic writing tasks) levels are reviewed. We conclude that the integration of handwriting practices into the educational program of beginning and developing writers is particularly important. It may allow the creation of solid basis for other writing abilities to flourish and therefore contribute to the emergence of capable and motivated writers.