He was born in Lipa, Batangas, on March 31, 1884. He was the third of four children of police chief Valerio Kalaw and Maria Manguiat. His siblings were scholar and political scientist Maximo, and two sisters, Rosario and Manuela. 

He finished his secondary studies at Instituto Rizal in Lipa, Batangas, and finished his bachelor's degree in arts with honors at Liceo de Manila.[2] He took up his law degree at Escuela de Derecho, where he was mentored by Rafael Palma and Juan Sumulong. In 1905, he topped the bar examinations, having obtained "grade of 100 percent in civil law and three other subjects" 

In 1909, Kalaw was elected the youngest member of the Philippine Assembly at age 25, representing Batangas's 3rd district.  

He died on December 4, 1940, aged 56