Farhan Qureshi (R.Madhavan) and Raju Rastogi (Sharman Joshi) are students at the Imperial College of Engineering (ICE), a highly regarded Indian engineering college. Farhan's passion is wildlife photography, but he pursues an engineering degree to appease his father. Raju chooses engineering with hopes of improving his family's financial situation, but his lack of self-confidence results in poor grades. Their third roommate and friend, Ranchodas 'Rancho' Shamaldas Chanchad (Aamir Khan), has immense interest in robotics, and invents in his spare time. Rancho regularly faces the wrath of the college's director, Dr. Viru Sahastrabuddhe (Boman Irani), known as "Virus", when he gives creative and unorthodox answers in class. He lives by the philosophy that one should pursue excellence, as when it is achieved, success follows. Virus is shown as an extremely strict person—so strict that he caused his own son's suicide by putting him under excess pressure. The star student of their class is Chatur Ramalingam (Omi Vaidya) nicknamed "Silencer", known for his incredible techniques of memorization but more notorious for his silent but malodorous flatulence in addition to his arrogant attitude. Catering for them and the other college students' needs is Man Mohan, nicknamed "Millimeter".
Indu (Shabana Azmi) and DK (Naseeruddin Shah) have a happy marriage and two daughters — Rinky and Minni — and live in Delhi. The tranquility of their life is interrupted when DK receives word that he has a son, the result of an affair with Bhavana (Supriya Pathak) during his visit to Nainital when his wife Indu was about to give birth to their first child Rinky. Bhavana did not tell DK about their son as she did not want to disturb DK's matrimonial life. Now that she has died, her guardian Masterji sends word to DK informing him that his son, Rahul (Jugal Hansraj), who is eight years old, needs a home. Despite the objections of Indu, who is devastated to learn of her husband's infidelity, DK brings the boy to stay with them in Delhi. Rahul is never told that DK is his father as he bonds with DK and his daughters. But Indu can't bear to look at him, a tangible reminder of DK's betrayal.
Ishaan Nandkishore Awasthi (Darsheel Safary) is an eight-year-old boy who dislikes school and fails every test or exam. He finds all subjects difficult, and is belittled and berated by his teachers and classmates. But Ishaan's internal world is rich with wonders that he is unable to convey to others, magical lands filled with colour and animated animals. He is an artist whose talent is unrecognised.
Mahavir Singh Phogat rêvait d'être lutteur professionnel et de remporter une médaille d'or pour l'Inde, mais a été contraint d'arrêter. Il place alors tous ses espoirs sur le fils qu'il aimerait avoir. Après la naissance de sa quatrième fille, il baisse les bras. Un jour, une mère vient se plaindre que ses fils ont été passés à tabac par les deux filles aînées de Phogat. Il découvre alors chez elles l'amour du combat, et décide de les entraîner à son sport de prédilection.
Professional photographers Vinod Chopra(Naseeruddin Shah) and Sudhir Mishra (Ravi Baswani) open a photo studio in the prestigious Haji Ali area in Mumbai, and hope to make enough money to keep it running. After a disastrous start, they are given some work by the editor of "Khabardar", a publication that exposes the scandalous lives of the rich and the famous. They accept it and start working with the editor, Shobha Sen (Bhakti Barve), on a story exposing the dealings between an unscrupulous builder, Tarneja (Pankaj Kapoor), and corrupt Municipal Commissioner D'Mello (Satish Shah). During their investigation, they find out that another builder Ahuja (Om Puri) too is involved in this dealing.
Vijay (Guru Dutt) is an unsuccessful poet whose works are not taken seriously by publishers or his brothers (who sell his poems as waste paper). Unable to bear their taunting that he is a good-for-nothing, he stays away from home and is often out on the streets. He encounters a good-hearted prostitute named Gulabo (Waheeda Rehman), who is enamoured with his poetry and falls in love with him. He also encounters his ex-girlfriend Meena (Mala Sinha) from college and finds out that she has married a big publisher Mr. Ghosh (Rehman) for financial security. Ghosh hires him as a servant to find out more about him and Meena. A dead beggar to whom Vijay gave his coat and whom he tries to save unsuccessfully from the path of a running train is mistaken for Vijay. Gulabo goes to Ghosh and gets his poems published. Ghosh does so feeling he can exploit the poems and make a killing. The poems are very successful. However, Vijay is alive and in the hospital after the train mishap.
At the beginning of the film, Kabir (Abhay Deol) proposes to Natasha (Kalki Koechlin). Their families meet at the engagement party where Natasha learns that Kabir is planning a three-week bachelor road trip to Spain with his school friends Imraan (Farhan Akhtar) and Arjun (Hrithik Roshan). Kabir explains that the three have a long-standing pact, and that during the road trip, each of them will have to pick an adventure sport, which all three will try together. Initially, Arjun is reluctant to take trip as he does not want lose his pay for missing work. It is later revealed that Arjun's ex-girlfriend left him due to his workaholism & obsesion with money. Imraan has an additional personal agenda on the trip: to find his biological father Salman Habib (Naseeruddin Shah), an artist in Spain.
Mohan Bhargava (Shah Rukh Khan) is a non-resident Indian working as a project manager at NASA. He had been a student at the University of Pennsylvania, an Ivy League school. After the death of his parents and 12 years in the US, he decides to return to his hometown, Delhi, in India to find his nanny, Kaveri Amma (Kishori Ballal), with whom he has lost touch. After visiting the old-age home where Kaveri Amma resided, he finds out through her friend that Kaveri Amma was taken to a village Charanpur.
The film starts in the 1960 Summer Olympics in Rome, where a coach says "Bhaag Milkha Bhaag!" The story is taken back to the memories of the childhood days of a young boy which haunted him, resulting in him dropping to fourth. Partition of India in 1947 caused chaos which resulted in mass religious violence in Punjab in British India, killing the parents of Milkha Singh (Farhan Akhtar). He reaches Delhi and later meets his sister there. Living in impoverished refugee camps, Milkha soon makes friends and survives by stealing along with his friends. He falls in love with Biro (Sonam Kapoor), but she asks him to live a life of honesty.
A gang of heavily armed men scour and finally narrow down on a house in Wasseypur. They surround the house and unleash a wave of bullets and grenades on it with the intention of killing the family inside it. After heavy firing on the house, they retreat from the crime scene in a vehicle, convinced they have killed everyone within. The leader of the gang then calls one JP Singh (Satya Anand) on his cell phone and reports that the family have been successfully executed but he is double crossed by JP Singh as a fire fight erupts between them and a police check post blocking their escape route. The scene cuts abruptly for a prologue by the narrator, Nasir.
In Sultanpur, a picturesque village in Pakistan, villagers have gathered to watch a game of cricket between India and Pakistan on television. Among them is a pregnant woman (Meher Vij) who, after giving birth, names her daughter Shahida after Shahid Afridi, the player who had won the game for Pakistan. On an afternoon, a six-year old Shahida falls off a cliff, but is saved by an overhanging tree. She loses her ability to speak from the accident. Her worried mother takes her to the shrine of Nizamuddin Auliya, a Sufi saint, in Delhi, on the belief that it would regain the latter's speech.
Murphy "Barfi" Johnson (Ranbir Kapoor) is an optimistic, street-wise, charming young man who was born deaf-mute to a Nepali couple in Darjeeling. His mother died when he was a baby and his father raised him alone, while working as a chauffeur. Barfi is known as a troublemaker – he cuts lampposts, plays practical jokes on innocent people, and is chased by Sudhanshu Dutta (Saurabh Shukla), a local police officer. Barfi meets Shruti Ghosh (Ileana D'Cruz), who has just arrived in Darjeeling; she is engaged to Ranjit Sengupta (Jisshu Sengupta), and is due to get married in three months, and Barfi is immediately smitten with Shruti. She also falls in love with Barfi but her mother dissuades her from pursuing him because he could not take care of her with his disabilities and lack of money. Shruti takes her mother's advice, gets married, and moves to Kolkata, breaking all contact with Barfi.
Jagadish (Vijay), a captain in the Indian Army, returns to Mumbai from Kashmir. On his arrival, his parents and younger sisters force him to see Nisha (Kajal Aggarwal), who they choose for him to be married to. At the bride-viewing ceremony, Jagadish makes up excuses to avoid marrying her, which includes commenting about her being old-fashioned. On the contrary, Nisha is a college-level boxer, who is completely modern in her outlook. Jagadish realises this and proposes to her, which she reciprocates.
The film begins with Michelle McNally (Rani Mukerji), a blind and deaf woman, visiting her former teacher Debraj Sahai (Amitabh Bachchan), who now has Alzheimer's disease, in a hospital. The film then flashbacks to the past to her childhood.
Murli Prasad Sharma (Sanjay Dutt), nicknamed "Munna Bhai" (literally "Brother Munna") is a bhai or gunda: a crime don in the Mumbai underworld. Given that his father had wished him to be a medical doctor, he creates the faux Sri Hari Prasad Sharma Charitable Hospital (named after his father) and pretends to live in accordance with this wish whenever his father (Sunil Dutt) and mother (Rohini Hattangadi) visit him in Mumbai.