In 1987, Kapadia appeared in Rajkumar Kohli's "Insaniyat Ke Dushman" and Mukul Anand's "Insaaf"; both action films that were popular with audiences. In "Insaaf", she played the dual role of a dancer and a physician. Later in the year, she played Pooja in Mahesh Bhatt's marital drama "Kaash". Kapadia and Jackie Shroff starred as an estranged couple who, during a relentless legal battle over the custody of their only son, learn that the boy is suffering from brain tumour and reunite to spend the last months of his life as a family. Before filming began, she called it the most serious artistic challenge of her career. Bhatt cast Kapadia because he was aware of her own marital experience and later revealed that during the shooting she had grown increasingly invested in the story, so much that after a point he could not differentiate her from Pooja as she "became the character". Kapadia's performance was praised by critics. Pritish Nandy, the editor of "The Illustrated Weekly of India", asserted: "Dimple achieves the impossible. Bereft of her glitzy make-up, glamour and filmi mannerisms, she comes alive as never before: beautiful, sensitive, intense. You almost feel you've discovered a new actress on the screen." In later years, "The Times of India" listed it as one of Kapadia's best performances, noting her "immense strength as a performer", and Sukanya Verma wrote of the "stoic determination and touching vulnerability" with which Pooja was played, calling the outcome "extremely believable and sympathetic at once". Bhawana Somaaya reported that "Kaash" had established Kapadia as a performing artiste.