Sl1-k2tog-psso (slip 1, knit 2 together, pass slipped stitch over) is a double decrease, meaning it decreases 2 stitches from the total stitch count.

It is worked in 3 steps, as you might imagine from the abbreviation sl1 …. k2tog ….. psso.  It is a left leaning decrease.

How to work sl1-k2tog-psso ::: 3 easy steps

1. Slip one stitch, knitwise, from the left hand to the right hand needle,
2. Knit the next two stitches on the left hand needle together (k2tog),
3. Using the left hand needle tip, lift the slipped stitch up and over the k2tog, and let it fall off the right hand needle tip.

One stitch remains on the RH needle, two stitches are decreased.  Note: slipping ‘knitwise’ means that when you insert your RH needle into the stitch, insert it from front to back, as if to knit.

This decrease is considered a left leaning decrease.  Other left leaning double decreases are SSSK (slip, slip, slip knit… similar to ssk) and k3tog-tbl (knit 3 stitches together through back loops).  For a right leaning double decrease try k3tog (knit 3 stitches together).

For a central double decrease (it is symmetrical and doesn’t ‘lean’ either direction), work sl2-k1-p2sso (slip 2, knit 1, pass 2 slipped stitches over).

How to work sl2-k1-p2sso ::: 3 easy steps

1. Slip 2 stitches together, inserting the RH needle tip from front to back through both stitches at once, as if you were working a k2tog,
2. Knit the next stitch from the left hand needle,
3. Using the left hand needle tip, left the 2 slipped stitches up and over the knitted stitch, and let them fall of the right hand needle tip.

One stitch remains on the RH needle, two stitches are decreased.