In a large bowl, combine the yogurt, marshmallows, and drained pineapple tidbits. Cover and chill for 2-3 hours, stirring occasionally. (Place the can of mandarin oranges in the fridge at the same time.)
After the marshmallows have started to soften and dissolve, stir in the mandarin oranges and coconut.
Serve immediately, or chill until ready to serve. Leftovers can be stored in the refrigerator in an airtight container for 3-4 days.
Notes
Traditional 5 cup salad calls for sour cream, but I prefer using lower fat plain yogurt. For a sweeter salad, you can use half sour cream and half Cool Whip or sweetened whipped cream.
Feel free to add chopped nuts and/or maraschino cherries.
I like using regular marshmallows, but you can use the fruit flavored variety.
I prefer the texture and flavor of the salad when the marshmallows are very soft because they sweeten the yogurt. But you can just chill the fruit, stir everything together, and serve it.