Was going to pass on this one but found that hauksdottir's comments about ambient lights were vastly different than my experience. So, let me give my lame concepts of the universe a shot: The Object color is added to the color of any light sources hitting a given pixel on the object. (actually, the inverse of the Object color is subtracted from the color of the light sources hitting the pixel, but thinking of it that way will scramble your brain) Ambient color is applied to the pixel even if none of the light sources actually strike that particular pixel. IMHO, using ANY Ambient color tends to produce unnatural, artificial results, i.e. omni-directional lighting with no source & no highlighting or shadow effects. This does not occur in the real world but can be used to mask problems resulting from otherwise ineffective lighting control. If there are "ugly black shadows" under the chin and arms, that is just because none of your light sources are hitting your figure in those areas. (A cheap shot perhaps but I strongly disagree with the above post) I do agree however, that ambienet light color can be used, on purpose, to create some very spooky and unnatural special effects, such as the glowing eyes she mentioned. Highlight color is pretty cool if used correctly. In the real world it would be a combination of the object color and the color of the light hitting the pixel, but Poser lets you make it anything you like. Setting the size is the cool part. This determines how "shiny" the object will appear. A small highlight size (and I'm going to take liberty with some terms here) will produce a small "focused" light "reflection" as might appear on a very shiny material. A larger highlight size will produce a broader, "unfocused" or diffused highlight as would appear on a material with a more irregular or coarse surface. If you are in a dim room right now, point to the bottom of your monitor so that your fingernail is backlit. To do that in Poser you would put a high luminance color and small highlight size on the nail material, but if you point again, you will see that the back of your hand is also highlighted, but less shiny. This would get a high luminance highlight color but this time with a larger highlight size on the slider. Perhaps a simpler example in Poser would be to take a square prop with a wave applied to it. With a small highlight size it would look shiny like plastic. As you increased the highlight size and diffused it, the material would appear less shiny and go from plastic to satin to silk to cotton. The Reflection color is just added to the color applied to the pixel from any reflection map used. There are check boxes to add the color of the light source and/or the Object color to the calculation of this color. If there is no reflection map applied, then this does nothing... I think. (Now that I think about it, I'm not sure what happens if you turn up the reflection sliders & just have a reflection color but don't use a R-map. Gonna have to go play with that one.)