We present a technique for measuring the coercivity of magneto‐optical and perpendicular recording media on a submicron scale using a magnetic force microscope and an electromagnet. Co–Cr coated silicon tips were used to write and image magnetic bits down to 150 nm in diameter. Bits were written when the sum of the tip stray field and an external fieldHextexceeded the local, or ‘‘point’’ coercivity. Media can be characterized by a continuous write probabilityPw(Hext) which differs significantly from bulk hysteresis loops. For an intermediate field range, writing was intermittent (0<Pw<1) due to spatial variations in media properties. ©1995 American Institute of Physics.