The　relationship　between　the　logit　model.　normal　discriminant　analysis　(NDA)　model.　and　the　mixtures　of　multivariate　normal　distributions　(MMND)　model　is　discussed.　It　is　shown　that　the　likelihood　equations　for　MMND　model　can　be　obtained　from　the　likelihood　equations　for　the　NDA　model　by　simply　replacing　the　index　variables　with　weights　that　are　the　logistic　probabilities.　and　that　all　three　models　use　the　same　linear　discriminant　function　to　classify　observations　into　different　populations.　Some　implications　of　these　relationships　for　data　analysis　are　also　discussed.