I am fairly new to knitting and am having a terrible time with gauge!
I have changed needle sizes up and down and usually end up with too few stitches per row and too many rows per inch. What am I doing wrong? I did try substituting a different year than the one called for the in the pattern but they are the same #4 worsted weight - could that be the problem or at least part of it? As I have look through the different brands of 4 ply yarns that I have - they all appear to be completely different from one another.
Appreciate the help

If you have too few stitches per inch, go with smaller needles. I’d try to get the stitches per inch right before worrying about the rows per inch. Depending on your pattern it might not matter as much.

Yes, The number of sts that you’re getting per inch will tell you which way to go in needle size. Take a look at the videos on gauge under the Free Videos tab at the top of this page, Getting Started. There’s lots of good advice on gauge which is so important.
Number of plies is an unreliable measure of yarn size and weight so go with the number system or the gauge given in the pattern in sts/inch.
Also, when you measure gauge, be sure to knit a good sized swatch, about 5"x5" or 6"x6". That way you can more accurately measure over the middle 4" and estimate your sts/inch.

Most patterns use a measurement for lengths, so the row gauge isn’t as important as matching stitch gauge.

A 4ply yarn is generally considered to be a fingering or sock weight; the #4 or 4ply worsted yarns are considerably heavier, like more than double the thickness. So maybe you’re a little confused on that. Here’s a page that might help.

As to gauge in general, CO 4-8 stitches more than the number of sts given for 4" and don’t include the edges when you measure how many sts are in 4". If there’s too many, the stitches are too small and you need a larger needle; if there’s not enough, the sts are too large and you need a smaller needle.

Thanks for your reply. I am obsessed with this little Mary Jane booties! and will not stop until I knit them up properly! The pattern called for Cascade superwash and I have been trying to use a Caron Simply Soft and I’m beginning to think that they are not interchangeable - I have a fingerling sock yarn and will give it a whirl with that - but first I will do a swatch - and if all else fails I will go to town and buy a skein of Cascade superwash.

The Cascade and Caron yarns should be similar enough, a fingering weight yarn (no L in it) is much much thinner. What gauge are you getting on what needles and what should you have?

Cascade also comes in a sport weight yarn. If the pattern calls for sport weight and you are using worsted weight you will have gauge problems. Can you link to the pattern or at least give us a name? There are a lot of Mary Jane bootie patterns.

What gauge is given in your pattern? Is it available online so you can provide a link?