If you fulfil the criteria for one of the five categories of ISN membership (given here), you can be admitted to the Society by filling in the membership form, get endorsement of two full members of the Society and by paying the requisite fees (Rs 2000 for full members and Rs 1000 for Associate members). Return the duly completed form, a photograph and the fee to the ISN Secratariat.
Click here to download the membership application. You will be taken to the login page where you will be asked to register on the website. In case you have already registered, you can use the credentials to login and proceed to download the form.