We estimate the luminosity function of field galaxies over a range of ten magnitudes ( -22 < M _ { B _ { J } } < -12 for H _ { 0 } = 100 km/s/Mpc ) by counting the number of faint APM galaxies around Stromlo-APM redshift survey galaxies at known distance . The faint end of the luminosity function rises steeply at M _ { B _ { J } } \approx - 15 , implying that the space density of dwarf galaxies is at least two times larger than predicted by a Schechter function with flat faint-end slope . Such a high abundance of dwarf galaxies at low redshift can help explain the observed number counts and redshift distributions of faint galaxies without invoking exotic models for galaxy evolution .